We went to Garden Grill last year for Thanksgiving Dinner and really enjoyed it. It was well worth the money we paid.
The atmosphere was great - revolving restaurant, plus the added benefit of the characters. Chip, Dale, Mickey & Pluto all stopped at our table even though it was myself, DH & DD (16). It was the first character meal we had ever done and my DH really enjoyed it.
But whichever restaurant you decide on, call bright & early on the 90 day mark. We had originally decided on LTT, but I forgot the day to call & missed getting in, luckily we had picked Garden Grill as a back up just in case.
When we went, we got there a little early and were in within a minute or two and did not have to wait for our PS time.