Parents 45Th Anniversary Gift

Do they enjoy dancing? Maybe host a small dance with cocktails and fancy snacks, serve a replica of their Wedding cake. People that age grew up going to dances every weekend.

You do not even need a band, get a DJ to play music from their era..

Send them away for a long weekend. There are some nice B&Bs on the Cape (I am assuming they live near you?) that are open all year. The beach can be gorgeous in the winter. Or of course a warm weekend is always nice too.

For my great aunt's 90th birthday, the grandkids and great-grand kids put on a skit of her life. It was sweet and funny! They told stories about her childhood, marriage & family, and her activism in the Civil Rights movement. My cousin taped the entire thing and gave copies to everyone.

Can you send them somewhere? A weekend/overnight/week trip?
B&B? Resort?
Do they have interests or hobbies to build a mini trip around?

For my parents 40th, we threw a 5 course tapas dinner for them and a select group of friends. They all loved it.

Have a few of their friends over for drinks & appetizers.
Re-create their wedding cake. A small replica of it.
Then give them a gift certificate for an overnight stay somewhere. Maybe
even include a gift certif for a nearby resaurant at their desination so
they can have dinner.

How about a spa day (couples massage). Depending on what you want to spend you could add a dinner and overnight stay at a hotel.
ETA: What about show tickets for them...not with you and the kids.

Ask them what they might want. Don't feel confined to "anniversary presents", but consider what might make each of them very happy. In my case, my dad would love a giant vat of honey, some fishing lures, some good socks, some quality meat. My mom would love, show tix, good walking shoes, a gift to charity, a nature walk.

See if thinking about each of them separately helps you come up with some better ideas.

best,
F. B.