We stayed in Tamarindo 2, the apartments on the other side of town from Tamarindo B&B. Our room was clean, the staff was friendly and attentive, and there was loads and loads of room. It was absolutely the best part of our stay in Cozumel.
The apartments were very quiet - we barely saw any of our neighbours - and ours had a great little kitchen and deck overlooking the pool. Tamarindo 2 is farther from the centre of town than the B&B, which has its pluses and minuses. The big plus would be the quiet, but then you're farther from the hustle-and-bustle...so take your pick, depending on which you prefer.
