As to FR placement: Keep in mind, most of the campaign map rivers are a fair size. There are undoubtedly others and the one in the Saltmarsh map doesn't look huge.
As to colour maps: Sorry, not in favour. I like clean references. Even if I'm on a VTT, but doubly so if I'm laying the thing on the table.
The real issue with many premade dungeon cardstock products (photopaper) is that artists need to put extra flourishes on every last little tile or photo map.... skeletons, broken swords or carts, little magical or lighting flourishes... all of which may be entirely out of place for where I want to use them.
I have a lot of Paizo, WotC and other tilesets of various sorts and a good 20% of them are contaminated with extraneous junk. A lot of the time, my groups are off in the deep woods, mountains, or the like. Finding giant skeletons, strange moai statues or odd magical lighting is just something that guts engagement when that isn't part of the product.
So, still in favour of information dense, black and white battle map presentation. If it is photo-real, there shouldn't be any little arty flourishes.
And while I'm at it, some sort of loo is likely a requirement in castles and some inns. Some inns and many churches might have an outhouse, but castles likely require facilities as do some inns. Yet you rarely see any facilities (sometimes not een a kitchen) as designers are too busy sticking in all manner of other things while ignoring baseline requirements.
That all said, U1 to U3 I've run and it formed a great part of a 20 year D&D campaign (20 real life years). One of the two brothers who help out the party (customs guys?) survived to become an adventurer in his own right (the other died). Great series for new or veteran players.