The air bags work great with the coil springs, so don't worry about that. I just find they are a bit expensive, and have a compressor that will require maintenance at some point.
I went with the Timbren SES system, and am very pleased. My truck normally is pulling about 6200lbs of trailer, and sits on the SES. I have not noticed any issues, but rather have noticed how nice the ride is when on the SES. It is not as rigid as it might appear. Gives more the feeling of 3/4 ton suspension.....firm, but flexible.
Airbag - adjustable
SES - Inexpensive and easy to install
Both are great choices IMO.