If I'm in a hurry to get to Portland I'll take I-84, otherwise, much prefer WA 14. As for places to stay, aside from Peach Beach or Mayhill, you might consider Crow Butte Park near Paterson, WA along 14 or further down and past Maryhill is Horsethief Lake; not a campground to really brag about however, the petroglyph panels are impressive. As an aside, we rarely camp on the Oregon side of the Gorge -- the rail traffic is intense and the proximity to I-84 can, at time, be problematic.
If you do take 14, consider stopping at Maryhill Museum; it's a gem in the middle of nowhere! And then there's the Stonehenge replica just before the 97/14 intersection. The replica was built by Sam Hill, the railroad magnate, as tribute to WW I soldiers from Klickitat County and as penance for Sam not serving due to his religious beliefs.