Just finished the Cascade Lakes Relay this weekend - it was my first running relay race, and it was AWESOME. I had a really great group of women in my van, which makes all the difference in the world, especially since we were one person short and had to split extra legs and cover more turns driving/navigating.
I ended up running just around 25 miles over the two days, which is almost more running than I've done period since Ironman last summer. Thankfully bike fitness did pretty well for me and I was able to maintain a decent pace for each of my legs (7.5 mi in 58', 7.5 mi in 1:02, 1.5mi in 15' (this was at 3:30am after already running, cooling down, and getting stiff... but we had an extra leg in the van to split since we were down a runner), 8.5 mi in 1:19). I had the first leg in Van 1, which was REALLY fortunate - when we handed off to Van 2 in the afternoon, the ground temp on the road was 118*. It was brutal. Thankfully our team stayed in pretty good shape over all - we were on each other's backs about staying hydrated and fed and rested.
There were definitely a few moments of the weekend where I had the thought "we just paid money to do this..." like when waiting in line for a portajohn, and again at dusk when I was getting absolutely swarmed by mosquitoes despite putting on 100% DEET stuff. That said, it was SO COOL to run at 3:30am with all of the stars in the sky and silence all around and the faint bobbing of other people's blinky lights who were also out on the road ahead of and behind me. I will definitely try to do this again, and highly recommend it to anyone. It's a lot less crazy than Hood 2 Coast and has some really, really beautiful scenery.
tl/dr - did a running relay, it was hella fun, would recommend.