Chris,
I too am from Seattle and have dove many times off the Kona. I've dove with a bunch of the outfitters on the island and each has been fun, but all have their quirks. So far have dove with Jack's Diving Locker, Dive Tek Hawaii (a tech diving oriented bunch), Pacific Rim Divers, and Wanna Dive. Wanna Dive does have a small boat. Last I heard it was being rebuilt, but I'm sure it's done by now. Another recommendation I'd give for a small (6 pack) boat is Pacific Rim (no relation to the Seattle area dive shop of similar name). Patrice is a great DM and knows where to find the good stuff. And the brownies she bakes for each day's diving are wonderful. She has a large returning client base so if you check her out and want to book with her I'd suggest you contact her early.
All of the boats I dove from, except for Jacks, left from the Honokohau boat harbor (about 5 miles north of Kailua-Kona). Jacks left from the town pier in Kailua-Kona. There really isn't any way to get to Honokohau without a rental car. When you dive with Jacks you meet at the shop at the south end of town and they shuttle you to the dock. There are some places where you can stay and walk to Jacks. But without a car you're pretty much limited to town and diving. And there's so much to do on the Big Island I've always rented a car.
For places to stay, it really depends on your budget. The best view I ever had from a room was at the Outrigger near the south end of Ali'i Drive. They have some rooms that literally hang out over the water. We'd watch the turtles in the tidal pools there all the time. It was great, but has gotten a little too expensive for what we were getting. At the Sheraton, even further south, they shine lights from the bar into the water and because of the lights it is one of the places that night Manta dives happen (the other Manta dive location is near the airport). And a Manta night dive is definitely a must do here. But just hanging out at the bar, watching the Mantas swoop and dive is pretty amazing. They've been there most nights. But probably the best deals can be found at VRBO.com. Vacation rentals by owner. Lots of houses and condos marketed by their owners. You're gambling a little more as to the quality of the room, but you can get some good deals.
If you want any more info on places I've been or outfitters I've dove with you can PM me. I know you'll have a great time. I've been there five times now and always have.
JB