We did both the Tea Party and Birthday Tea Party in December. Both were held at Lucky Nugget. We had prepaid for both and when we booked the Tea Party was at Pizza Planet and the Birthday Tea Party was at Lucky Nugget, just before we left we found out that they had been combined and the Tea Party was now at Lucky Nugget too, but as we had prepaid we still did both.
Now you would expect that being at the same place, they would have been the same experience. No, not so. For the Tea Party we were seated upstairs. Upstairs there was hardly any food, a very small food selection and also no hot drinks!, it was very very disappointing, there were also hardly any characters, we could see them downstairs and when some would pop upstairs, they were mobbed and quite honestly, NOT ONE stopped by us, where we were sitting. My DS went downstairs to get some food as we could see the buffet downstairs had a lot more food (larger selection) that we had, a few others followed suit and also went downstairs to get coffee and food, but not everyone up there, as we were not told that we could go downstairs. Anyway, hence we left that Tea Party, very disappointed, so much so that I complained on our way out to the manager, I thought it was a rip off!
Despite this we returned a few days later to Lucky Nugget for the Birthday Tea Party, we were so tempted to just blow it off as it was so bad the time before, but we had already paid, so we thought we may as well. It was much better!, we were seated downstairs, had the larger selection on the buffet, we had the cake, the birthday card for the characters to sign and then the Mickey toy gift at the end. Characters were much better, we saw many more than the first time, but still there were characters there, that we hadn't seen in the park and DS wanted the autographs, but they came out went around half of the room (obviously it was the other half), were mobbed , then left and didn't come near us (or our row)
So in conclusion, the Birthday Tea Party, whilst at the same venue and at the same time as the Tea Party, is MUCH better than just doing the Tea Party. So I would book the Birthday Tea Party (and celebrate somebodies upcoming or past birthday). I would never again waste my money or time doing the regular Tea Party, unless it changed in some way.