G00SE

I've had marginal success with this in the past, it's really helped me out when I've given Niche airlines a try (Like a SoCal Commuter line and such)

I had an airline that was exclusively max capacity 747-400D's one time operating out of the busiest hubs in the US towards anywhere they could land in North America. I'm sure plenty of people hated me when I did that but it was worth the laugh. Ultimately, It's great for High Density routes as longs as you're not crossing oceans with it. It's Cheap compared to all the others, and holds plenty of people (Though for everyone's sakes, maybe do more than just max economy seating), plus it has a comically short runway requirement that can park it just about anywhere you'd want to fly (I believe it can even do KSNA). Have a small supply and put it as the flagship for your best transcon flights.

I did an airline out of Moscow once, that flew almost exclusively to places in the former USSR just for laughs and giggles and after having a bunch of liquidity, I leased a truckload of TU-144's, running them between All Three of Moscow's Airports to Eastern European regions. Not very long flights, limited competition, and a cheap tactic I use for my IFS which gets me an additional $200 or so per seat (I mainly use that so I don't have to worry about being shut down by spamlines or so I can do little cittyhopper flights that would otherwise not be possible to make a profit with) kept me out of the red. It's the only time I've gone all in on Supersonic, though I've been thinking of trying again.