We came back from the Riu Bambu in March after having a great holiday. There are activities going on for most of the day which should suit most teenagers e.g. volleyball, archery, pool games, etc. etc. etc. Buffet restaurants are "go when you want" although the brochure does actually say 2 sittings, we found that in reality it was not. Speciality restaurants ARE 2 sittings. WiFi is free but is restricted to the reception lobby area only (not in rooms). The room refurbishments in the Bambu are just about complete but I believe that they are shutting it down very soon to refurbish the recreation areas (pool, bars etc). Residents of the Bambu can also use all the facilities of another 2 RIU hotels (the Taino and Naiboa) and are free to walk around the 2 Palace hotels but cannot use their facilities (except the Caribbean speciality restaurant in the Palace Macao which you have to prebook in the morning).
Having been to the North of the Island (Sosua, Puerto Plata) and the Bambu in Bavaro, I prefer the Bavaro area. The sea is a lot calmer as it is mostly the Caribbean sea whereas the North is the Atlantic. The beach is also stunning at Bavaro and we never had any bother with sand flies.

Cheers

Keith