Glenwood and the Ark are about the easiest shuttle hitchikes around. If you're running to Three Rivers Park in Glenwood, drop your car at the parking lot, take your PFD or a paddle to identify you as a boater (so folks won't think you're a Rainbow-type, God forbid...), trot up the bikepath to the I-70 exit and stick out your thumb. You'll soon be on the way back up to Grizzley Creek. No slam on Dee but you should spend the $35 taking the lady out to a nice restaurant.
Take the bike if you want to run Shoshone. Its also easy to hitch from South Canyon or New Castle though from New Castle it's about a 15 minute walk back from the boat ramp to I-70.
There should be plenty of boaters on a weekend to catch rides with.
Have a fun time!
Nothing in the world is more yielding and gentle than water. Yet it has no equal for conquering the resistant and tough. The flexible can overcome the unbending; the soft can overcome the hard. - Lao Tse