Even if a tour operator isn't contracted with the hotel you choose, it still can be done.
Last year we found out that the Siam Bayshore (Pattaya) was in renovation and we chose to move to the Woodlands... but the tour operator didn't sell it. My older and very experienced travel agent told the TO how to get around it. We did pay more though as it was a more expensive hotel.
The Holiday Inn just near the Patong Merlin have family rooms and it's a lovely hotel.
Cheers Geri