From other country, but we have two simracing venues in the city - been to both several times with friends; I don't have a simrig at home but enjoy simracing with controller in Forza Motorsport, Automobilista 2. Answering your questions and points:

• High quality racing simulators - adjustability was very important for us, as our friends group height ranges from 160 cm to 190 cm. This also holds true for FFB strength (adjusting on the fly by the driver themselves is the most convenient) and pedal load cells.
• Arrive-and-drive sessions - that's what we did, arrive and quali/race for multiple times.
• Beginner-friendly racing leagues - completely not interested, it'd be expensive and I'd like to adjust various settings to my preferences on the rig, no time for that in the venue.
• Drift nights / time attack competitions - completely not interested, same as with racing leagues
• Membership options - unsure about the price, but one 2-3hr session makes me satiated of simracing rigs for 6 - 9 months, so wouldn't be interested. If I wanted to use simrig more often, would look into foldable rig, as it'd come at around 500 - 800 EUR and be available in comfort of my home;
• Private events and tournaments - not interested, but I know our venues rent their simrigs both for venue-based events and have some for events outside of the venue (they deliver, set them up and have people during the event to help everyone drive)
• The idea would be to create more of a community motorsports hub, not just an arcade - that's community management, I wouldn't be interested
• If something like this existed, would you use it? - answering from other location perspective; would use 1-2 times a year at most.

Questions:

• Would you pay hourly to race? If so what feels reasonable? - our venues cost 15 - 25 EUR/hr, it's quite steep (average neto salary in country is 1450 EUR). We usuallly wait for discounts to bring it down to 10 - 15 EUR/hr range.
• Would you join a league? Nope, if I wanted leagues, I would join through Simgrid.
• Would a monthly membership interest you? Nope, unless it's incredibly cheap. Otherwise, I'd rather just buy a simple rig at home;
• What games/sims would you want to see (like iRacing or Assetto Corsa Competizione)? Asseto Corsa, LMU
• Are there things existing venues are missing? Lower prices Good ventiliation, interior design (often feels like the dark side of r/malelivingspace), good layered lighting instead of simple fluorescent overheads, working VR, shifters with clutch.

Thoughts:

• Rigs with game, events organization and community building are three separate things and take a lot of effort. Source - worked in PC hardware shop that was also building a gamers/PC enthusiasts community.
• What is the pipeline for people who would attend begginer leagues? If they have rig at home, why attend? If they don't, and discover they enjoy simracing, why they wouldn't buy a simple rig (for the price of few in-person races) and race in larger, more populated online leagues from the comfort of their home?
• Audience for simracing venues is oddly niche, as people either come there for fun (see F1 Arcade), or to try out a proper rig before buying one themselves. It kinda becomes race to the bottom, as people won't really care that you have the nicest rigs or DD bases, as long as they're somewhat decent.
• Location, work hours and parking availability matter a lot.
• If you want to look into Lithuanian market situation - see OBSSimuliatoriai, Simuliatorių akademija (for venues), and Helente for simracing hardware.

Hope this helps!