III Forks would be a great choice, the price of the steaks includes your sides so it's really a better deal in my opinion than the other higher end places that do a la carte sides.
An anniversary dinner would be the time to splurge a bit, and if you're going to spend $28 on a steak at a bar like The Belmont I would hope you could go $33 or $36 for a true steakhouse.
I will also give a nod to III forks, but note that III forks prices are noticeably higher than those at Ruth Chris.
A menu with prices for III forks can be viewed here:
If that link doesn't work, simply go to
Choose "Austin", then go to the scroll down menu and choose "III Forks"
Prices are more in the $35-$45 range at III forks.
This is not necessarily a pure "steakhouse," but the ribeye at The Belmont is just terrific in my opinion.
"Brown sugar and ancho crusted ribeye" with crab stuffed tomato and a spinach/bacon salad
I think it's really solid.
The crab cakes are quite good also, in my opinion.
Austin chronicle readers rank this restaurant at 12 for 2008 as well
The dish is $28, but the serving is extremely generous in my opinion. I think you get a lot of food for your dollar.