I have stayed on the Garden side hotel rooms on many occasions. I like several rooms for different reasons which I will share with you.

Room # 15 which is on the 2nd floor far left. Its close to the office and pool, but its easy to access from the stairs and a tad bit larger room and balcony. You also don't have an ajoining balcony door with your neighbors (not that I have ever had any issues with that, and I think they lock etc).
Room # 11 or 12. Room #11 is on the opposite end of Room #15 on the 2nd floor. Both Room 11 & 12 have a nice view of the ocean. You may hear some road noise, its really no biggie and slows down after the sunset tours up to Ricks end. Both of these rooms are great and I think you would be very happy in either. Actually I have never had ANY bad rooms at Xtabi.
Now on a different note my hubby likes 1st floor Room # 19. It stays cooler and darker in the mornings. I don't mind the sun shining thru the windows in the morning, but he loved its being a little more dim and nice and cool.

Funny thing is we have tried to get over to the cliff side and rent a cottage, but honestly after almost a dozen stays at Xtabi we always end up in the Garden side and very happy to do so. It's not that far from the cliffs & ocean. We bring our snorkeling gear and setup on a chair, we never have had anyone mess with anything of ours. Its a very family feel to the hotel. Sharon the head housekeeper is jewel. Wonderful woman. And while Xtabi always tells me they have a small refrigerator, it never happens. BUT Sharon will setup you up with nice hard sided cooler and ensure you have ice at very expensive charge when you need it.