My experience & some suggestions for single-wall...

(1) I've had a Bibler I tent for about 4 years now which I use for 4-season use - I LOVE this tent!
(2) I used to primarily use my OR Advanced Bivy when BPing in the Sierra in the summer... 2 Lbs is hard to beat!
(3) I do more solo now than ever, wanted to make sure that I had someplace to at least change clothes if I needed to or it was raining, etc., so I started looking for lightweight CHEAP solo tents... there is one you can get at Sports Authority called the "Ranger", sells for $20.00 - weighs 3 lbs! I've used it a coupel times, not a bad product at all for the price, but you need to be shorter than me (I'm 5'10" and had to sleep cross-wide in it - not a big deal, but thought I should mention)
(4) Came to the conclusion that while the cheap-o Ranger has it's place, I also wanted what I call a "real" tent that I would feel more confident in as my primary place of residence should I end up in a rainy situation where I needed a vestibule for cooking, etc., so I recently purchased the North face Tadpole while it was on sale @REI. Like the Bibler I tent, they market it as a 2 person tent, but the reality is they're both really a comfy solo tent!

(Oh, and I'm also an old guy over 50!)