Here's my attempt at a megaship.
I've docked up 2 "snub" SSTO fighters that I'll drop off at Laythe for refueling purposes. It doesn't show it, but it's got 1.5 Million Delta V. This sucker could pull 8 G's in vacuum with a half load of fuel (but no refueling ships).
BUT this was really dragging down my computer. I decided to deorbit / destroy all the space junk around Kerbin before I made my run to Jool. There was a science ship with 6 astronauts that I had entirely forgot about! Building the big ship, I had sent every kerbol up in either the main ship or the snubs, so lucky to find those guys just floating out there.
Others can make such attractive big ships, mine just looks like a retarded squid.