A tourism visa is what she'd be seeking. The application is done online. What will be required is
(1) Statement of employment from her employer, stating years of service and salary
(2) Bank statements from previous 12 months
(3) Any land/property ownership documents
(4) Immediate family details
I do it every year for my lady. The first is probably the hardest, but with a good record of non-overstay it gets easier. In the last few years she's also had visas for UK three times and Schengen twice
I did it last week at CW. Maybe some provincial offices have a different policy. I know Bangkok Bank in Bangkok haven't stamped the statements for the last three years and will now accept the emailed 12-month statement. Pattaya has more dodgy agents than anywhere else in Thailand so it's possible they are paranoid?