Hi Joe,
I'm an iron on man myself. I do use tissue on free flight models and some control line but time contraints and impatience cause me to use films and also I like the finished look, durability and strength gained by using film. I can throw a few models in the back of the car without worrying about breaking the tissue (or silkspan).
For larger models, I really like the Super Monokote, because I have found it doesn't go slack in the sun - especially white. But it is heavy.
For general use I like Solarfim, because it sticks really well and is easy to work with and is lighter than regular monokote. However I do use regular monokote too as I usually buy by colour availablity reather than film type.
For light models (including 1/2A and some free flight) I use the Coverite 21st Century Microlite film, at 0.6 grams / sq metre it's great, irons on beautifly, stretches, and shrinks really well. It is a bit fragile though and punctures easily. It's primarily designed for Park Flyers.
I avoid everything else with the exception of Coverite Coverlite tissue, but this is not really iron on, it is heat shrink tissue. Not as light as Microlite, but much stronger and more durable.
For trim I like to use the monokote trim sheets as they stick they the preverbial and are easy to cut and apply.
I hope this helps you in your quest.
Cheers