...so I'll be the first to share what I know about my plans.
As of now I expect to depart Decorah very early in the morning on Thursday, May 14th. My route takes me up US-52N to Preston, MN, then west on MN-16 where I quickly hook up with I-90W for the bulk of the transit. I'm guessing I might be the only EIMer who uses this "northern route" since it's likely a lot more convenient for the CR-IC area folks to take I-80 through Omaha.
I haven't yet decided on the final part of the route. It's unlikely that I'll go all the way south to meet the group in Alliance on Thursday afternoon. I'm considering heading southwest on SD-44 at Cactus Flats -- looks like an interesting road around the south side of Badlands NP. I might look to rendezvous with the big group of MINIs heading north at the intersection of US-18 and US-385 as an option, or I might just head straight to Hill City and wait for everyone there. I'll post my final intentions when they're firm.
Hill City is going to be my personal base of operations for the event. I have reservations at the Best Western Golden Spike Inn in Hill City for three nights starting Thursday night.