Hi Laura
We had 5 nights on Samui this time last year. We stayed at the Baan Chaweng Beach resort (it is a boutiquish style resort, reasonably intimate and off the main thoroughfare but easy walking distance to restaurants, shops and bars).

Prices were affordable, central location, friendly/helpful staff, great beach, plenty of private lounges, beachside restaurant, rooms were fantastic with private verandah, pool was on the smallish side but never crowded.

If we returned to Samui we would definitely stay at Baan Chaweng again

Cheers - Leo