It's going to be difficult to get to Utila in under 6 hrs. - it was for us from Phoenix. If you can get to Roatan by noon, taking the ferries will get you there by 5PM. Return puts you back on Roatan around noon for the flight back. One place you may want to consider on Utila is Deep Blue Utila. They have an $850/wk AI rate starting in July? that includes everything (except alcohol) - includes 3 boat dives/day. The food was good, the rooms were clean and there's a shore dive (actually 2 sites) just off their beach.
http://www.deepblueutila.com/
It's really quiet there though at night since it's by itself across the lagoon channel from town - all travel is by boat. It's one of 3 AI's on the island, the other two are Laguna Beach and Utopia Village. They're equally isolated on the south side. I haven't been to Belize but some of the best diving we've done recently was off Utila. Saw a lot of big pelagics, a few sharks, lots of grouper, some big triggerfish, barracuda, eels etc. And the reef is very healthy and in a lot of areas really shallow - breaking the surface in some locations. There's also snorkeling with the Whale Sharks but you won't be there at the optimum time for that. They do see them all year though. If someone does all the boat captains will notify each other so you can go looking after your morning dives. We snorkeled with six over two days - it's an awesome experience.
One of the people staying with us on Utila flew from the Portland area. It was 12+ hrs. and 3 connections. Well over $1200 2 years ago IIRC. We were able to get an inexpensive ($600) flight to Roatan and the ferries are $102 r/t. Staying in town in Utila can be very inexpensive, it's a backpacking destination so there's some really cheap accommodations - some of them dorm style. Also there's a lot of dive training done there so finding a dive operator is easy.
Or since you haven't dove Roatan yet either there are some AI possibilities there. The most known is Cocoview - I've never been there but it gets great reviews here. Cocoview really has about the only decent shore dive on Roatan except for Reef House Resort - which IDK anything about either. Across the channel from Cocoview is Fantasy Island - it's been kind of hit/miss lately going thru several mgmt. changes and remodeling. It was very cheap when my friends stayed there last year but they said they got what they paid for.
Anthony's Key Resort on the north side has the Dolphins and overwater bungalows. Full AI also. Barefoot Caye on the south side is a little more upscale than either. They really do provide the valet diving service they advertise. Mostly what you'll see on Roatan is smaller stuff but a lot of it in some areas. We did see turtles, some bigger grouper, stingrays etc. on the north side dives. No sharks and the only dolphins were at AKR - although there are some wild ones spotted on the south east side occasionally. The only sharks were at the Waihuka/Cara y Cara Shark Dive but it's more advanced due to currents and possible conditions at the site.
Nightlife that exists on Roatan is based in the West End, you can put together some diving/lodging combos in that area reasonably - Coconut Tree Divers is one but for a full AI look at Luna Beach Resort. Anthony's Key is only about a 10min. cab ride from that area also.
You might look at Curacao also. It's the same excellent diving as Bonaire but with more to do. Bonaire has many AI's but you can't get there in 6 hrs. - from our side of the country it's usually the Friday night red-eye thru Houston on United. We're able to get to Curacao from here in about 7-8 hrs. thru MIA or IAH, connections thru LAX might be better. The diving is really good, lots of stuff to see, easy beach entries in most areas but a short swim out to the reef is often required. Turtles, rays, lots of eels, squid, lobster, an occasional octopus were pretty common - and thousands of fish everywhere. Since it's shore diving you can keep the costs down substantially - just rent a vehicle.
Lions Dive and Breezes are AI options in Willemstad. I've been to but not stayed at Lions Dive - it seemed nice. Ocean Encounters is next door and the Seaquarium complex is next to it. For $200 you can dive with the Dolphins just offshore there. There's also several restaurants and other things to do nearby. And it's 5mins. to downtown from that area.
Lodge Kura Hulanda is a more expensive option out in Westpunt - approx 45min. from town - not sure if they bundle diving though. There's also All West Apts. there, they both use Go West Diving. Westpunt is really quiet at night - just a small town with a couple of restaurants.
Personally we found the diving to be better on the west side. The Dive Bus is an excellent option for escorted shore dives also - do a couple days with them to get a sense of diving there then go out on your own. Entries are easy and the reef parallels the shoreline so it's hard to get lost. Almost every dive we did (20+) was mostly at about 60' - it's where the good stuff was found. Tugboat is one of the signature dives, the boat is at 20'. Playa Kalki in Westpunt - IMO the best shore dive there - we stayed around 50' - more vertical walls in that area. At Varsenbaai there were seahorses at 40' a boat wreck at 80' and turtles at 6' along the shore.
At many of the dive sites there's an on-site operator for tanks/wgts. If you need full gear, you can get that there at many locations also. The main Ocean Encounters shop next to Lions Dive had a lot of decent looking rental gear.
hth,
