What size batches are you doing now? Make sure whatever you build is capable to expand to bigger batches. On my stand I made sure the base where my kettles sits could hold my smallest kettle (original HLT was smaller than brew kettle) but was wide enough to accommodate bigger kettles in the future. I didn't however quite anticipate the height of a bigger kettle and when I got my 20 Gal boilermaker I found it would be nice if my stand was a little shorter due to the overall height.
My HLT is on a controller and pumps are manual. Having a HERMS on a controller rocks, I can step mash, mash out, etc and have perfectly controlled mash temps and let it manage itself while I clean, sanitize...ok really just drink beer and relax.
Plan for room for a heat exchanger or counterflow in relation to kettles, pumps etc. Also I would recommend swivel wheels that locks, they make it easy to move things around for cleaning or just better positioning. Lastly you will likely find that you need to tweak the height, placement of your burners so keep that in mind when mounting whatever will hold your burners.