Welcome aboard!
I have a 37 Nordic Tug, hull #15, built in 2000. I've had the boat for three years and have taken it to AK each summer—about 2000 hours of running time total. I really like the boat!
It's super efficient. I typically cruise at 1300 rpm, making about 8 knots and burning a little more than 2 gallons per hour. With 370 gallons of fuel onboard, there's plenty of range for any coastal cruising.
The boat is easy to single hand (pilothouse doors and bow thruster!) and there's enough space to have guests.
NT generally selected good quality components and installed them well. I've done lots of upgrading, but haven't had to redo or fix anything because NT installed it poorly or it failed prematurely.
American Tugs tend to be newer (they started building boats in 2000 I believe, NT in the 1980s), and thus more expensive. The 34/365 AT is similar to the 37 Nordic, but with one stateroom instead of two. The AT also has a slightly shorter salon/galley and slightly larger head. Nordic also built some single stateroom 37s...they're really nice boats if you rarely/never have guests aboard.
Let me know if you have specific questions or want to see a NT37 in person but without a salesman. My boat is in Seattle right now but I'll be cruising in the San Juans, Gulf Islands, and hopefully up to Princess Louisa starting next week. Back in Seattle for the boat show in January.
I bought my Nordic through Steve Scruggs, the factory-direct salesman for American Tug. He's knowledgeable and fun to work with....recommended. There are a bunch of good 37s on the market right now in the PNW, and these boats are small enough that they can be shipped relatively economically.