Does anyone have experience traveling from Tapachula to Panajachel by bus? Any recommendations?

You can find just about any bus route and schedule within Mexico on ticketbus.com.mx site, but since you want to go on to Guatemala, you might want to post your question on lonelyplanet thorntree - more active for bus travel further afield etc on that site than here I think. .. . I got some more detailed routing info over there when I was planning our itinerary a few months ago . ..

I agree - search 1st and then ask:
http://www.lonelyplanet.com/thorntre...spa?forumID=12