As a gay person I'm happy to see the legalization of gay marriage in Thailand and plan to marry my partner of 11 years in February.
I plan to maintain my annual Visa extensions as a "Single Retired Person" versus applying for a "Marriage Visa" which is always an option. Some would prefer the Marriage Visa option as it cuts the financial income requirements in half, although immigration performs house visits periodically to validate that the couple is still living together with this type of visa which I'm not interested in.
Some farang who marry their Thai counterparts either have a formal Buddhist Wedding Ceremony, which normally involves the Thais family and friends, followed by having the marriage Registered, or the choose to forego the formal ceremony and simply have the marriage registered. A personal choice.
Getting a marriage Registered is a fairly straightforward process. Once the necessary documents are acquired, the Registration can be completed at the local Amphur.
The primary reasons why we've decided to marry are, 1) faster and easier for my partner to obtain tourist visa if we ever want to visit my home country (USA), 2) Lowers the complexities and/or risks involved with my Last Will in the event I die, and 3) Gives my partner full authorization to make medical decisions for me in the event I'm ever in a life-threatening situation in a Thai hospital.