Stuff to see on our last trip to Vegas (for a while)

My wife and I will be heading down to Vegas in December. We usually go about 2-4 times a year. But now there's a baby on the way, and we probably won't be back for at least a few years, maybe longer.

We've seen pretty much everything on the strip and downtown. We have been to a few of the outlying casinos (although the wonderfully cheesy laser show at Sam's Town is the only thing we really liked).

Some of the things we plan on hitting up this last time around:
Pinball Museum
New Hoover Dam bridge (and she's never been to the dam before)
Neon Museum
a Dotty's?

We might go to the Stratosphere. We haven't been in about 6 years, and they've added a lot of new rides. Are any of them worth the money?

Anything we're missing in the outlying area? We love free entertainment like the anamatronic shows. But non-free stuff is cool too.
I don't think we need restaurant recommendations. That's pretty well covered in other threads.
Note: We're not outdoorsy people so hiking/climbing stuff is not what we're looking for.

You may like the Atomic Testing Museum on Flamingo Rd.

If you haven't been to Red Rock Canyon out on Charleston, you should check that out if you have a rental car. They have a little Visitor's Center, and you can see a lot of the area from the comfort of your car on the scenic drive.

This might seem a little weird, but ... my sister thinks she was kidnapped by aliens, so on one of my trips to Vegas, I took an afternoon to go to the A-le-Inn in Rachel, out by Area 51, to get her some little green man souvenirs (which she LOVED).

Anyway, the drive out there was really unique - large valleys, miles of straight roads, hardly *any* traffic. One of the things I did was to stop by the side of the road by a stack of gravel, and just lean back on the pile facing the valley. Literally, there was no sound at all, outside of an occasional wind gust. Nothing. It was AWESOME!

Very nice juxtaposition to the Vegas noise. But maybe not something you'd want to do on your last trip for a while, now that I think of it.