From Croatia, the best place to fly back from would be Zagreb (in Croatia), but there is nothing direct to home. We live in the Midwest too and typically fly from Minneapolis to Amsterdam to Zagreb and Dubrovnik. If we go with United/Lufthansa, it would be from Minneapolis to Chicago to Munich to Zagreb and Dubrovnik.

As for the beaches...

I love Dubrovnik. I has become very touristy though, but has some nice Hotels to stay in. If you want cultural/architecture, Dubrovnik is an option. Split, further up the coast with its own airport, would be a great spot too. It is home to Diocletian's Palace. The better beaches in this area are a little out of town or on an island (Brac - Zlatni Rat Beach).

Depending on what matters most, you will find that Croatia is like few other places with its diverse scenery. Since my first trip in 1987, as a 14 year old, it has become very touristy.

Just came back from a holiday around Split. Rocky beaches but clear and lovely. If you have time to get to the islands, I suspect the beaches will be even nicer. We were in Hvar several years back and I remember a lovely beach as well.

very close to venice (100 miles) cape kamenjak beaches south of the village of premantura. stay in rovinj, visit pula with one of the best preserved roman amphiteaters in the world. great food both on the coast and in inland istria

http://www.likecroatia.hr/news-tips/destinations/ten-amazing-beaches/
http://www.likecroatia.hr/dine-wine-cat/istria-and-kvarner

The Island of Brac is amazing if you want a realxing place with unspoilt beauty. From Brac Island you can explore some delightful places from like, Bol with its lovely Dominican Monastry built in the 15th centurey, you'll be close to the famous Zlatni-Rat beach, the tranquil village of Postira and much more. If you like island hopping around its a lot of a fun.
A suggestion for places to stay would be http://www.croatiabeachvacations.com who specialise in Brac Island.

Most people consider Dubrovnik a must-see, but I've always preferred Split, which has archeological interest - and a quiet public beach (Bene beach): the city's antidote to Bačvice Beach, which I also call Plaža Pepeljara (Ashtray Beach).

20 minutes on a passenger katamaran brings you to the island of Šolta, which has some quaint villages and "secret" coves.

I always tell visitors to go to the island of Vis, and its south shore: Komiža. There's diving, rock climbing, and the beach at Stiniva, which is as frequently photographed as Zlatni Rat, but not nearly as touristy, not even in high season.

Anyone have specific resort hotel with swimming pool and beach access to recommend? Looking for place to relax after 2 1/2 weeks of hard sightseeing in Italy. Thanks!

You might want to take a look at this old thread:

http://www.fodors.com/community/europe/croatia-beach-resorts.cfm

About a hour south of Zadar looks really nice. Not much there but houses and coves. I would love to go back and just sit in a chair and stare at the blue water. Also area around the Bosnia 1 1.2 hours north of Dubrovnik looks real nice.