ROUND TABLES AT A CEREMONY?!?!?

Most vendors should adjust to what you want, especially since you are paying so much for it. At my venue they said one option would be to have the ceremony inside with the chairs in rows, then we would have a cocktail hours so we can take pics then they would set up the room during that time. I don't see why they can't do something like that. However, I think that if the tables are nicely decorated and as long as you don't have plates on them or anything that's fine. I have seen this done on a few TV shows and while it may not be your first choice it is in no way tacky

This is actually what we did because we also only had one room to work with. It turned out beautiful. Not only that, the guests didn't have to go anywhere between the ceremony and reception. It worked out well for us.

Thats what I am doing, so I don't find it tacky. I actually find it more comfortable.

My cousin actually did this. He and his now wife planned to hold the ceremony on the beach outside the hotel and the reception in the hotel ballroom. Mother Nature had other plans, however, and dropped the outskirts of a hurricane on us! No evacuation was necessary, but it made for some interesting views from the ballroom! Anyway, they re-adjusted. They formed their aisle from the room entrance to the dance floor where the ceremony was set up. The ushers were situated at the door to the ballroom and, instead of guests seating themselves via escort cards, the ushers escorted us to the tables we would be sitting at for the reception. Everyone had a great view of the ceremony and we knew exactly where we were supposed to be for dinner. It worked out really well and wasn't at all tacky! It was beautiful! Good luck!