Dubrovnik and Split. Maybe a cruise around islands like Korcula and Hvar. Zagreb's nice but no wildly different from other central European capitals, and not a particularly touristy place. Food's not as cheap as it was, but still reasonable.
just to add that beaches are mostly (though not entirely) rock/pebble until you get down to the south, where they start to become very nice sand. Pula has a nice Roman amphitheatre if you like ancient remains.
Been here twice in the last few years stayed on the Dalmation coast at Porec which is a very beautiful coast line. It has fantastic eating places although most hotels are half board and the people here are really friendly and welcoming. Stayed in Dubrovnik and the experience was completly different, people at this end are not as friendly all geared to getting your money, Dubrovnik old town very expensive and full of cruise liner tourist guides.