Thanks for all the info, budge would be less than $400/night total if possible. Looking forward to this. Some beach time, some exploring, food/drink, and photography.
If diving is a major focus of your trip, then you might want to look at places that have an onsite dive op. These are less likely to be family destinations so they will be quiet and they are more convenient for diving and usually the diving is cheaper. You will need a car but since you like to go exploring you will probably want a car anyway.
These places on GC are on the water but not on 7MB, but some of them offer unlimited shore diving on their house reef, which can provide more dives at a lower costs per dive; but be aware that the shore dives may be winded out during the winter months, especially as you go further north of 7MB in West Bay.
The lodgings that have an onsite dive op include Sunset House (Sunset Divers, breakfast included), Lighthouse Point (Dive Tech, also services the Grand Caymanian Holiday Inn), Cobalt Coast (Reef Divers, they offer an all-inclusive package or cottages with/wo the meal package), Coconut Bay Condos (I think they only have 3 bedroom condos?) and Compass Point (Ocean Frontiers, no shore diving, and quite distant from the beach and most restaurants, but good diving).
Most other condos and hotels will have a relationship with a dive op and they will pick you up if you stay on 7MB (either by boat or van) and you may get a better deal on a dive package if you book the condo and dive package together in advance.
Another way to reduce dive costs on GC is to focus on shore diving, often around $12-$15 for a tank and weights and with a dive op onsite. But you will need a buddy, they are not keen on solo diving in the Caymans - are you both divers?
In addition to the shore dive locations that I mentioned with the dive resorts above, Turtle Reef/Macabuca (Sundivers) and both Eden Rock and Lobster Pot (both are in George Town so avoid the time periods of 10 am to 3 pm when the cruise ship passengers are in town).
When you say that you like photography and exploring, do you mean nature and wildlife or do you want to be in a popular tourist destination with great restaurants, shops, and nightlife? It's your vacation so whatever works for you - and if you want a gorgeous, endless white sand beach and great restaurants and tourist activities - then Grand Cayman will be perfect for you - but it will be expensive during the holidays and it is likely to be crowded, although a condo will be much more private than a hotel.
But if you are mostly interested in nature and wildflife and good diving, and since you like quiet, you might also want to look at the Sister Islands of Cayman Brac and Little Cayman. These are tiny, rural islands, not at all crowded, with great diving. The popular lodgings are on sandy beaches but they are not great swimming beaches.
The Cayman Brac Beach Resort and the Little Cayman Beach Resort are all-inclusive and the lodgings are modest but clean and modern and the food is buffet but it is very, very good.
The Condos at Little Cayman are more private but they are affiliated with the LCBR and offer packages for diving and food if desired. The Southern Cross Club on LC is more upscale and they also offer a meal package. Pirates Point is another dive resort and they are said to have the best food on the island, but they serve a pre-fixe menu each day and the choices are limited. I think that they only offer 2 dives per day but they are long dives. They are on the water but I don't know if they have a beach, as they are on the point.
Paradise Villas are also on LC and near the Hungry Iguana restaurant but that is the only restaurant on the island so the menu will be limited.
We really like the Sister Islands and feel that the diving is better, especially Bloody Bay Wall and Jackson's Bight off LC.
There's not much to do on Brac and Little Cayman but relax, dive, eat, sleep, and enjoy nature. Cayman Brac has interesting topography with nature trails and caving available. The Sister Island resorts offer entertainments for their guests and the CBBR and LCBR have small spas and gyms onsite.
We love all 3 Cayman islands and there are a lot of options in a variety of price ranges, you just have to figure out what you want to do on vacation and how much you can afford to spend.
When we are on GC we prefer staying at a condo and preparing some simple meals and going out to eat because there are many great restaurants, and we tend to do shore diving, and snorkeling and some boat dives on GC because there are lots of other things to do.
When we are on the Sister Islands of Brac or Little, we prefer to focus on boat diving and stay at an all-inclusive dive resort (CBBR or LCBR) because that is easy, the resorts are small and nice, and there aren't many other choices available.
Good luck!