Go to the Redwood Bar & Grill at the California Hotel, downtown. The prime rib is awesome, and reasonable. Someone (Jim P.?) once posted that the prime rib is black angus, though the rest of their menu items aren't angus. Someone else (Tammy, I'm pretty sure) posted that they have a special that isn't on the menu...but I don't remember what the special is!

Anyway, last time we were in Vegas we wanted to take my brother and his wife (first-timers) out for a nice dinner, and that's where we took them. It was our first time there, and the prime rib dinners were some of the best we've had in years.

I believe they recommend reservations.

Congratulations and enjoy the celebration!

here's a link to a site with some ratings and comments:
http://www.ieatvegas.com/restaurants/ratings/rate79.html