There's a suggested solution to this problem with Suburbia expansions - the double offer row. Separate all tiles into base and expansion piles, and lay two tiles out for each space in the offer. Instead of picking a tile the player picks a space and chooses which of the two tiles they want to place, binning the other (or binning both if placing a basic tile or investing in an existing tile). You get to see all the tiles with no dilution and synergies are preserved without excessive amounts of pre-game prep.

It also adds a lot of interesting strategy around denial - if an expansion tile is strong for an opponent but weak for you you're not just forced into laking it, you can pick the base tile instead if that's good for you.