Are there any tourist visa extension options in Thailand for a US passport holder beyond the initial 30 days?

You’re option is to do the 30 day extension, then either do a border run or a quick 24 trip to another country by air and then do the same process again. 120 days.

As Tod said...you can do a maximum of 2 LAND BORDER entries into Thailand EACH CALENDAR YEAR. AND Each entry allows you to get one 30 day extension of stay at your local Thai Immigration office for 1900 Thai baht.

Make sure whenever you apply for a 30 day extension of stay , you have a TM30 address registration on file with Thai Immigration.

Nope.

No. 30 days and your done

unless you're married to a thai or have half thai children, you do NOT

You're allowed ONE 30 day extension on a 30 day visa exempt entry for 1900baht at the immigration office where you stay, then you're done

If you want more time in thailand you either exit/re-enter to get a new 30 day visa exempt entry (which you can do 2 times a year by land) OR you go to a thai consulate in a nearby country and buy a tourist visa that stamps you in for 60 days when you arrive