We pulled it off!
I took the kids to breakfast this AM while Collin 'ran a couple of errands'. He hustled to TRUs to pick up three bikes and retrieved the other from my neighbor's garage. He then set them up in the living room and met us for cup of coffee.
We were coming home to open presents so they decided to forego the visit to Santa until later today or tomorrow and dive into presents. (which works out nicely b/c Amanda was going to ask Santa for a bike; now she has to think of something else --hint-hint: maybe ask for that Look-Alike doll you wanted)

To say they were shocked is an understatement - the squels and shrieking could have burst our ear drums. Perfect! They had a blast opening and have been happily playing all day.

Let's see...
Ian's favorite - his Hot Wheels car hauler/truck
Amanda's favorite - her doll stroller and/or her camera
Sean's favorite - the pogo stick and his Tech Deck stuff
Maggie's favorite - her Barbie house stuff

Now, if we have snow at Grandma's there Christmas will be complete.