I use a Kryptonite KryptoLock (combination U-lock) around the seatstays. My bike is parked in a pretty secure location (underground parking garage, in full view of the parking attendant who I'm always friendly with) and occasionally briefly locked up at the grocery store, so I don't feel a need for a heavy-duty locking system. I don't lock the front wheel, it is a nice handbuilt Mavic/Mavic wheel with QR, but the fender attachment method also requires the QR to be unscrewed and removed in order to remove the front wheel, so it isn't a 5 second theft job. It also makes repairing flats kind of a pain. I don't use any theft protection on my saddle - it only cost $30 on eBay anyway.

All my life, I have always used U locks - I had the very first Kryptonites, with the flat strap "U" - and have never lost a bike to theft. Back in school days I would remove the front wheel and lock it with the seat tube and rear wheel.

My son locked his hybrid bike outside his middle school for three years, occasionally even overnight (yes, I chastised him), with the same Kryptolock around the frame only, and that bike was also never stolen. It isn't a high value bike so the level of theft protection was adequate. He is getting a nicer bike for high school, so I will at least instruct him to lock around the seatstay.

My "nice bike" for weekend rides is never locked, because it never leaves my side. When I stop for post-ride coffee or food, I bring the bike into the coffee shop with me; any place that doesn't permit this, I don't patronize.

My daughter will bring her upgraded UO-8 to college in the fall. Judging from my visit to campus, it will be one of the nicer bikes in the racks. The dorm has a card-entry bike cage. I'll send her with a U lock and we may use Pitlocks instead of QRs. Alternatively, I might drill a hole through the QR lever and use a small padlock to secure the lever to the fork.