I guess I've never actually played electric guitars (as in strats and teles and such) and acoustic-electric guitars at the same show. I've done a bunch of gigs with electric guitars and mandolins though. For typical electric guitars, it's whatever amp I'm using at the time (AC30, AC15, Deluxe, Vibroverb, etc.) + pedalboard. For mandolin, I've used a teeny little board with Peterson Strobostomp as tuner/DI, a delay, and a MXR Micro Amp, to the PA. The MXR boost is mostly there as sort of a Linus' security blanket in case I get an anemic signal through the house system. At one point I was running both instruments through my guitar rig for convenience, but the mandolin tones sucked.
I do a lot of acoustic-electric work these days. I use a Radial J48 active DI, and if I'm supplying sound, a Mackie system. I use a small Phil Jones Cub acoustic amp as a monitor to push a little air behind me. This works pretty well for the acoustic-electric and electric instruments I carry - a guitar, a high string guitar, an electric banjo, an electric sitar, a mandolin, and a couple of lap steels. It's taken me a long time to get the bugs worked out, but I can use the same pedalboard for A/E work as I do for electric guitars.
There's always some sort of compromise though, so I just gauge by what the bulk of the work will be about. If it's electric guitar intensive, most of my efforts go toward choosing the right tube amp. If it's primarily an A/E thing, my priority is DI/PA.