246epa, it so happens I posted this very question a couple years ago by way of a thread called "cheap cars for tall guys". You'll find it here:
http://www.canadiandriver.com/forum/index.php/topic,52979.msg403248.html#msg403248I don't mind the Impala either, though they aren't particularly reliable. Stay away from anything older than an 03--the reliability data is terrible before that.
I agree that the Crown Vic/Grand Marquis are good, reliable cars. Enormous. You still see lots around used as taxis, which should tell you something.
Buicks are generally reliable and a good buy. Buick Regals are cheap and (don't tell your son) generally driven by older drivers, meaning you should be able to find one that's been looked after. Same story for the LeSabre, which is basically a highway cruiser. These were upscale cars that offer a lot of features for the money on the used market. But be prepared for relentless grandpa jokes.
I bought an 01 Subaru Outback, which has been great (I'm 6'5"), but I had to shell out $8,500 for one with over 200,000 km (but this was 2 years ago). So, possibly not in your budget.
I eliminated a lot of cars just by going to a dealership and sitting in them.
Good luck!