1. Immigration here is a breeze (esp. compared with another place I have experience, Chiang Mai). For a rental you show a copy of tabiian-baan ID card, and owner's phone. What could be easier?
2. Air is good. There is usually a slight breeze which helps with the heat.
3. Gulf of Thailand sucks in terms of wave actions and cleanliness as compared with Krabi, Khao Lak, Phuket. As you lived in BKK, this is probably a "don't care" for you.
4. There must be at least 50 decent restaurants in HH. Seems to me that might be enuf for anyone.
5. Rentals are widely available at decent prices. Determine your area, drive around to find rentals. Services exist to help, I find them useless
6. HH is a 180 baht minivan ride and 4 hrs from BKK. Train is easy too, but more expensive and slower.
7. Can get daily newspapers easily, not true of other places I have lived
8. Availability of Thai language schools in HH is poor (similar to every other place I have lived except CM)
9. Two hour ferry to the eastern shore of the gulf, but expensive
10. Excellent bus service direct to/from BKK airport, ~370 baht
11. Hospitals in abundance
12. There is not an abundance of gyms, but enough
13. Easy access to the south of the country via bus or rail.
14. No airport to speak of. One flight to KL. A plus for me as a committed low-carbon Luddite
15. Enough bar action and associated pool, darts leagues.
16. I am told the golfing is great
17. Phetkasem Rd traffic can be a pain but nothing compared with BKK
18. See https://en.wikivoyage.org/wiki/Hua_Hin