Saddlebags with built in light
 

I have a good taillight with rubber straps that go around the seatpost, but the metal hook the straps connect to is scratching it. I have a good saddlebag(s), but have been interested in something a little larger that I could fit my cellphone in, though that's not a big deal. I've found two different ones, wondering if there are any reviews on them and if there are any others out there.

Saddle Lite LED Bike Saddle Bag

Louis Garneau Little LG-Race Saddle Bag - Backed by a 100% Satisfaction Guarantee | TriVillage.com

I'm not too excited by the design of either bag. I'd rather have a bag with a reflective loop that can hold a rear light. That way you can use any quality rear blinkie. This will give you a much better rear light. I'm partial to Jandd products; I've used them a lot over the years and they are rock solid. This hurricane mini mtn wedge will do the trick, Hurricane Mini Mountain Wedge

There are larger versions of this as well.

You might put some tape or plastic film on the seatpost under where the metal hooks are..

I just recently bought that LG bag. It seems well made and about the size I was looking for but I haven't really had a chance to see if the light is bright enough out on the road. It seems just ok testing inside. Definitely not a NR Solas (2 watt). It's not on the bike I usually ride at night so it was more for if I got caught out later than expected. I doubt the battery life would be enough for long night rides. It's just a button cell battery.

I haven't had much luck with any bags with a loop for a tail light. They tend to sag, bounce and not point in the correct direction after a while. I prefer a seat post mount.

I like the idea of a separate bag and light. The bag will outlast a light.

Just a +1 on all the replies so far; weak light from built-ins, sagging clip ons, and easy scratch proofing with tape.

I'd add that simply changing the seTpost light to a higher quality unit is another way to go.

Another vote for a bag with a loop so you can attach whatever blinkie you'd like on there.