Luton (or at least the airport) turned out to be surprisingly unsucky, at least on a weekday. As they were only using ⅕th of the checkin desks, but probably ⅓rd of the departure lounge, I have this horrid feeling that it will be heaving during the weekends of package holiday/charter flight season, but I've no intent of finding that out first hand. Then again, I wasn't planning to fly out via Luton until about 22 hours before the plane took off.
Given that I had to depart before 9:30, I had to buy a full fair ticket (which turns out to be a princely £31 from Grove Park, a mere £2 more than the off-peak price to Stansted Airport). As I was blowing the budget already with full-fare, I thought about asking the ticket office person what the cost of first class was, but I didn't. The irony was that the 09:00 Derby service from St Pancras (first stop Luton Airport Parkway) was only 5 coaches, so to prevent overcrowding in standard class, they'd de-classified half of first class. So I got to travel first class anyway.
Those hourly Derby services seem to be rather nice. The train goes like the clappers (we passed 3 Thameslinks† on the way), first stop is the right stop, and even with a maximal 10 minute wait for the airport bus and an 8 minute bus ride, it was still faster than the Stansted "Express". (46 minutes, including a stop at Totenham Hale and one other station. Stansed is to "Express" as Tiscali is to "unlimited")
Despite this I still prefer City. But there one needs to book early, or be filthy rich.
† The slower service to Luton Airport Parkway. Semi-fast Thamelinks take 30 or so minutes, stopping Thameslinks take 40