Thanks Tobias,
I appreciate the input. I still haven't come to any conclusion yet, but I know there are some good options. If only my budget wasn't an issue I would buy them all!
Shameless self-plug, but one of my goals in creating
the Pirate Coast expansion was to encourage compact play by setting up a shoreline along 1-2 edges of the table. It features a few new mechanics, but you could also easily use the coast as a river-esque starting position. Most of my games with the expansion have been fairly compact. Maybe you'll find it helpful!
If you're keen to try it but don't like all the non-base game tiles just let me know and I'll make you up a version using only cities, roads and cloisters.