Hi!
You're right Tholos is fairly quiet - most of the restaurants and bars are along the one main street through the resort. It's not always quiet though, i've had a few good nights there with the right crowd.
You can easily visit other resorts as the local buses run along the main coast road through Paradissi, Kremasti, Trianda and Ixia to Rhodes Town. Along time since i've got a taxi back from Rhodes Town to Tholos but i'd guess you'll pay around 18/20 euros. It's very easy to get back as there are taxi ranks in Rhodes Town or you can just flag one down in the street.
If you take the local bus in the opposite direction you can visit Ancient Kamiros and just down from there is an excellent beach (much better than the resort beaches on this coast).
If you're self catering don't miss the old village of Tholos. There's an excellent greek taverna hidden in the small village streets - great food and much cheaper than the tourist restaurants. Walk down the main street to the petrol station, turn left, up the hill and then left into the village.