What are you talking about? Old memories perhaps? Nowadays, it's not a particular challenging route or adventure, particularly not since the Cambodian road from the border to Siem Reap was completely paved in 2009. It's one of the better intercity highway stretches in Cambodia now. With some advance research, it's not that hard to get a good description of options to get to Thai-Cambo border, scam avoidance, the crossing itself, and then the rest of the trip. One should allow a day (7-8 hours incl crossing time) to do the entire route though.

BKK-REP flights are a pricey PG monopoly but if you've GotBucks, it's the quickest way. Alternative option priced between the all-overland or the PG flight, is flight BKK-PNH then private car or public bus between PNH and REP. However, when you figure in the front-end time to BKK and check-in, immigration, security, etc, time savings over the all-overland from BKK might end up being nothing, when all is said and done.

However you get there, a trip to Angkor is absolutely worth the effort. Try to spend about 3 full days there.