It's been awhile since I've been to BKK and need some advice.

Will arrive BKK via CX from BOM at 1025 and need to find way to Khaoyoy, Petchbury.

Was actually planning to get out of there same day 1840 H but beginning to think those things still don't happen in BKK! So looks like hotel for the night.

Any suggestions?

Thanks

Can you clarify your plans? You arrive BKK at what time? You want to proceed immediately to Khao Yoi, Petchaburi that same day, and possibly return to BAngkok later that same day? Budget? Day of week?

A train might be possible, from Hua Lamphong, a bus is certainly possible, from the southern bus terminal. Taxi, mini-van, private car, rental car are also other options. It looks like ~ 150 Km from Suvarnabhumi to Khao Yoi. I have no idea how long it might take to drive

Based on my best guess of your intentions, it might be best to hire a taxi or private car for the trip down, have them wait for you and then take you back to Bangkok later that same day.