I am sick of flights that are "preassembled" (I don't know the right word) by aggregators. I am willing to pay a bit more to buy one ticket and not need to recheck my bags at every stop. Further, I would like to be able to build in a fun day with a long layover in BKK. Are there any sites or services that let you choose all the legs and then buy it as a complete ticket?

1 hour layover in Korea - do people actually make their connections in these cases? shortest one ive had.