Class A with four 3 point seat belts (ie, shoulder straps)

Not sure what you budget is, but Newmar had a model for a few years ( maybe 2006 thru 2010) called the Allstar I believe, which had some models with 4 captains chairs in the front. You can do an Internet search to see how they are configured, or look at the archives in Newmars site for their archive of old literature.
I saw PPL in Texas had a diesel powered Simca from Safari with 4 captains chairs in the front, but it's a 38 foot toy hauler which might not fit your needs, although it's priced pretty well.