If your companion wants a beach - there's none at Sunset House. It does have a popular outdoor bar. Also it's walking distance to south Georgetown and just west of the airport so a short cab ride if you don't rent a car (driving is on the left there) Another SH advantage is it's likely the easiest place to find a buddy for shore diving there - everybody is a diver or with one. Easy entry from the Saltwater Pool and 2-3 decent shallower dives - the Mermaid, the small Nicholson wreck and ask the shop when the tourist sub goes by to wave at them.
Cayman is pretty pricey for everything as it's mostly all imported.
If you select any of the resorts along Seven Mile Beach (the Westin is pretty nice) any of the dive operators will pick you up by van and take you to their boats daily. 2 dives and you'll be back b4 noon. Most also do 1 or 2 tank afternoon dives or specialty dives,
Every operator puts a DM in the water - often 2 based on the group's experience level. Most 2 tank dives are a deep wall dive followed by a shallow 2nd dive - often at a different site. The one gotcha about the deep wall dives are the moorings are often around 60' or so - above that all you're diving in is blue water. Not always though - more often at some of the north wall sites where the first thing you encounter might be the pinnacle or whatever feature gives the site it's name rising from the depths.
There are also a lot of really good shallow boar dives - Aquarium was a good dive. Only about 60-70' max with lots of coral heads and several cleaning stations. My buddy got his cuticles trimmed at one by a banded coral shrimp.
Also there's the Kittiwake - it's both a dive cleaned wreck you can penetrate and a snorkel for your friend - the top of the ship is about 10-15' down. A recent storm tore the wheelhouse roof off - it's that shallow.
You also could both do Stingray City but find a dive operator that takes snorkelers instead of one of the more popular Sand Bar snorkel trips which are really just wading with stingrays.
You can dive and participate in the feed and your friend can snorkel down - it's 14' deep. You can hand them squid as they swim down so they can also participate in the feeding.
I personally wouldn't stay anywhere else for 4 days. The East End requires a 45min+ drive and even the quieter south side is about 20mins. from most things with very limited food options etc. Most of Caynan activities are either around downtown - including multiple cruise ships per day - or mid Seven Mile Beach.
Many of the lodging options also have on-site dive operations but generally it's just an office - their boats are elsewhere. Seven Mile Beach is a nice white sandy beach but the diving is a few minutes ride offshore - at the Westin or Marriott Red Sail will sometimes beach a boat and pickup divers but most of them keep boats in the Sound and dive the North Wall/ NW area. A lot of the best of the Cayman dives are there.
A few other options - there's a dive operation at Sunshine Suites. Also Ambassador Divers at the Comfort Suites would probably work for you .
www.Cita.ky lists about 2 dozen others.
