Caye Caulker doesn't have any 'nicer' beach than does Ambergris Caye, per say.... At least nothing like Can Cun or Miami Beach.
But hey, if that is what you are looking for, then why come to Belize, right?
The whole island of Caye Caulker is sand - like Ambergris Caye - and we are not as populated, which allows more 'beach' space, so to speak. But really, most people hang out at the Split for swimming, snorkeling and sunbathing - at least those who don't have accommodations with these facilities ( like a dock or deck, or tanning area.
As far as accommodations are concerned, it varies according to amenities.
You have Iguana Reef Inn, Caye Caulker Condos, Diane's Beach House, Auxillou Suites, Lazy Iguana Bed & Breakfast on the 'higher end' of things. Some with the full works like Full Kitchen, Living Room Cable TV, A/C etc.
And then you have the mid-range to lower end. Check out: www.gocayecaulker.com
for a listing of accommodations on the island.