We had a great Auxiliary in Milwaukee when I was there. There are some that just lounge around and don't like to do any actual work but for the most part ours were mostly all gung-ho and ready to go. They actively played a roll in our day to day operations particularily on the weekends and holidays. As you stated, they can't play a direct roll in LE operations but we used them extensively for Search and Rescue, basic safety patrol and security operations. We even used our Auxiliary to supliment our station after a particularily long rescue where they would cover the station communications and the guys on the boats would patrol and respond to any non-LE related calls so our duty boat crew could get some sleep. Doing security perimiters for things like fireworks and other shoreline type events and helping with searches and rescues was the bread and butter of our Auxiliary guys and they were awesome. We worked really closely with our guys and we even had a couple that we used as communications specialists sort of and they would even help with communications and organization for some LE operations, they would just have to stay at the station or in our command truck. I joined for a short period after I left Active Duty Coast Guard but then moved and didn't have the time to continue.
I would strongly recommend joining and helping out, depending on your unit and area it can be a lot of fun and a lot of excitement.
One thing I can't speak on is aviation. We never used any Auxiliary CG with aviation, it was always just our active duty guys with the exception of occassionally using the Civil Air Patrol but not in our aircraft and not really that often as the nearest CAP was way up in Northern Wisconsin...
I am a Paladin, like the warriors of old, ready to stand on the line to keep others safe... A Sheep Dog, ready to protect the herd from advancing wolves!