I'd go for an "experience" sort of gift - something they might be more likely to do if they had a little nudge from you. For example, a museum (art, sculpture, science, historical), an aquarium or a botanical garden membership (so they can visit anytime at the drop of a hat, and enjoy discounts at special programs, the gift shop, the café, etc.). If they live near water, try a whale watch or a river cruise. Around here, there's a section with a ton of restaurants, and they have 1 or 2 "restaurant week" programs during the year, in which you buy a fixed price ticket and then have options about a main course at one place, dessert at another, etc. There are also a lot of farm-to-table restaurants popping up everywhere, merging local growers and regional cuisine/wines. Those can be mini-adventures.
If they enjoy movies together, look for a film series in their area (try colleges too), or get movie tickets from a theater (or even AAA) and package with gift certificate for popcorn/snacks and maybe a pub-style dinner nearby (whatever they like). You could package it in one of those popcorn containers or even get an empty one from the theater, then jazz it up with cellophane and ribbon.
Are they outdoorsy? How about a canoe trip or kayak rental, guided or otherwise, or a membership to a nature area or network of them, with new lightweight backpacks & stainless steel water bottles. You can get those printed at some camping places - their first names, their initials and wedding date, whatever you want.
Do they love wine? How about a wine tasting subscription? When we were in the Napa./Sonoma area, we found wine stores that sold wines from local vineyards, and which would engrave a wine bottle (your choice of any wine you like) with the couple's names and wedding date, then ship it to them. It makes a nice first anniversary gift.
I'm sure you can think of other things along these lines - go with their interests and less on an item for their house since they are well-equipped now.