Keeping 'Big Kid' Toys Away from Baby

I have kids the same ages! My daughter hasn't become too mobile yet, but I'm nervous for when she does. I'll be getting rid of all the small pieces!

You need to ALSO teach your Eldest child, about baby safety.
He is 3 years old. He can learn that.
If you explain to him. But sure, you still have to supervise.

When I had my 2nd child, my daughter was 3 almost 4 years old. I simply taught her and explained about baby. Her baby brother. I explained 'safety', choking, how to handle her baby brother, explained baby development to her. ie: that babies cry, nurse and cannot do things like she can, nor can they handle things like she can. That babies can choke, that they like to 'mouth' things and it is not safe. That small things are dangerous. etc.

You need to teach your Eldest, about these things, too.
How to keep 'his' things, separate, and to 'try his best'.
But still supervise. Teach him what items, are not safe for baby.
Have a basket, for him nearby, to keep his things in.
That if baby grabs something small, to take it from baby and out of reach etc.
I taught my daughter those things, once I had my 2nd child.

We put those toys in a bin (toys with small pieces) and keep it up so that we are completely in charge of when those toys are played with. We still let them play with those toys, just usually during naps, or when I am able to 100% supervise. Then they get cleaned back up and put away.

We insinuated the rule that if older child didn't put it away mom put it away in a big box in her closet and for every day you put ALL your toys away after you were done playing with them, you got 1 piece back (my daughter has polly pockets and we allowed for 1 outfit back or 1 doll back, but not all the polly stuff back all at once).

First of all, you are doing the right thing by keeping things neat and organized, that's half the battle!
I know others have suggested gating off his bedroom, but it's not usually realistic to keep all of a child's toys in the bedroom, especially if said room is far away from the rest of the house.
My son was the same age as yours when my daughter was born. He learned early on that the baby could choke on small pieces and he was very diligent and sweet about helping me to keep her safe :)
Most of his toys at that age were pretty safe, balls, building blocks, etc. But once he started getting into legos and other little things, I kept those in plastic bins with lids and he played with them at the table. That worked pretty well. The other thing to remember is LESS IS MORE. Just keep the overall amount of toys in check and things will be much easier to manage!

I saw a table in a catalog for legos...and had my dad make one for my son when my daughter was born. We kept all the small pieces on the table, and it was high enough that DD couldn't reach it.

It is so hard! At the beginning I kept the toys with smaller pieces in my daughter's room or put them in the closet and brough them out only at certain times. But, the older my little one gets (now 19 mos) it's just that much harder. He wants whatever she has and he still likes to put things in his mouth, so it's tough. We also have some shelves in our family room and I woudl put those toys on higher shelves so my 3 y;/o could get them on her own but mow my son is able to climb up and get htem himself! ACK! I'd say do whatever works but keep in mind you may have to continually change it up and you'll probably have to let the little one play with more stuff while keeping more of an eye on her.

Kids like to play where the action is.

In your case, here are two suggestions that give you control and some safety over the situation.

First, when your bigger one wants to play with "little pieces" but be close to you, set up a portacrib/pack-n-play in the livingroom. That is HIS space to play, and the little pieces must stay in the portacrib. This way, the pieces are contained (he can come back to them) and might not fall on the floor, much as they could at the table. (Which is another option, working "up".)

Also, consider investing in a good gate for your son's room. This way, when your daughter is mobile, you can gate the room off. He can play in there but still feel more connected because the door won't be closed. This will also keep out little sister. I like the gates which have hinges and lock into place instead of the pressure/tension gates which can fall over.

As time goes on, you'll discover that you invent other ways to keep your older child's play protected and separate. I would also be clear that if little pieces are left out, that they go away for a week or so. You can make the clean-up fun, though, and be :"hunters" for whatever you need to pick up. Make a game out of it.

(When I was 8 and my brother very new, we had a rule when sewing that she would count out all of our pins... if any one was missing when we cleaned up, we'd have to search until we found it, so our little brother wouldn't choke. Just an idea for seriously dangerous things for baby: counting out how many and then making sure all of them are cleaned up.)

you just have to keep the toys in a room the baby can't get into like your son's room if they don't share a room.
Tell him to keep his toys in one area and that they are not allowed out of it.

You got some good answers, but I just wanted to add another tip. Running the vaccuum often in the area where she'll be roaming around on the floor will help make sure that nothing small was left behind (that you can't spot) or even that a leaf or something isn't laying on the floor from someone's shoes or something.

My youngest was 2 when my niece was born and once she started playing on the floor him and his cousins were all really good at keeping small toys off of the floor so she couldn't get them. I would put all small toys up on shelves your 3 year old can play with them while she naps or at a table or in his room. At 3 he is old enough to understand that the small toys aren't good for baby.

The kids have different bedrooms here. Their toys stay in their rooms or they go into time out. Barbie shoes are yummy chew toys for in infant so we keep all things separate.

In child care centers kids have to be 3 years old or older to play with ANY toy that can fit through a toilet paper tube. If it fits into it it's not allowed in any other rooms. It is often odd to a parent who brings their child to a child care setting and they can't play with hot wheels cars at the center. They play with them at home all the time. So many times parents just don't think about it. Good for you that you are paying attention and taking measures to make sure the baby is safe.

There are tons of food that are choke hazards too, marshmallows, raisins, nuts, chips, grapes, so many...you can find a list online by googling foods that are a choke hazard.