Is it plausible for you to take them to the mall. Your older one can walk around & burn off energy & the your baby in the stroller.
Build a semi large fort in the living room.
Will you allow the 2 1/2 year old to watch part of an animated DV like teh movie "Cars" or some other one?
Build blocks
Play w/matchbox cars
Some of these only last a few mins each but...
Kick around a few blown up ballons in the living room
bring out all your stuffed animals. Line them up, toss them.
Toss around some bean bags in the living room
Let your baby play w/some tupperware & lids on a blanket if he/she can sit up.
Have a puppet shwo (just a few hand puppets)
have the older one put together one of those wood puzzles w/the animal cut outs (only about 6 pcs & easy to put in)
Put on cartoons.
Stack throw pillows in living room & knock down.
If you have those soft, square blocks...fun to build with.
Hang in there & good luck.