20-23 Days/Nights to Backpack…

In your position I'd head to some of the higher SW desert areas: Grand Gulch, Dark Canyon, the Escalante, Zion, North Rim on the Grand Canyon (which while technically not open in early May, will be accessible). What I'd recommend would depend on your experience and comfort in negotiating water concerns and hiking cross country in such environments.

Those parks sound amazing, but having no experience hiking canyon, I am a bit hesitant to hike in canyon country. I do have significant backpacking experience otherwise, though. I'd like to try those areas though.

+1 on Grand Gulch and Escalante

If uncomfortable with pure desert, maybe the higher grasslands of New Mexico and perhaps lower altitude Colorado (see PMags post trip report)? Just look at trails with a perennial water supply and updated fire info. Later in May, New Mexico might get too hot however (there's been a drought but it's forest specific).

Do a 3-4 day loop in Canyonlands, Needles district to start. Do a week in Dark Canyon next, hit Coyote Gulch and the Escalante for 3-5 days, finish with rim-river-rim on the North Kaibab.

At the end of May you'll be well on your way to being a desert hiking expert.

Escalante via David's suggestion sounds like something I really need to look into. That sounds pretty darn amazing! Thanks so much.

I wholeheartedly second DAve suggestions of heading to the desert. Consider booking a commercial guided technical canyoneering outing early in your trip. This will let you see some amazing places and gain some knowledge of the area to feel more comfortable when you set off by yourself. It would be money well spent. That area is a great place to hike, and your time of year is perfect too.
Cheers

How wonderful to get such wonderful, helpful suggestions. Thank you all very much. Time to do some quick research of the mentioned possibilities. :-)

Be aware that by later May it will probably be real hot in the desert SW, so slot canyons & places with water would be preferred. Buckskin-Paria canyons would be a nice option. Trans-Zion would probably be ok, being a bit high.

Our Happy Maze loop would be nice, if you are facile with navigation:
http://adventurerun.wordpress.com/2013/04/25/happy-maze-loop/#more-906

Someone suggested Needles & Dark Canyon. These can be linked in an excellent loop by traveling south from Squaw Flat (Needles) into Beef Basin via the Hayduke Trail (route), into Fable Valley, over to Youngs Canyon & down into Dark Canyon, then up Dark to exit via Trail Canyon, then work your way via nice dirt roads to Cathedral Butte & the TH for Salt Creek, which takes you back to Squaw Flat. Many other options exist. Be aware that water is very limited. The SW experienced a very dry winter, so water is especially scarce throughout the region.

Could hike most or parts of the southern PCT – Mexican border to Kennedy Meadows, maybe farther depending on timing northbound. If you start at the border in early May you'll be behind most of the pack, but not too late in the desert. Little snow in the mountains. Check PCTA on which sections still closed by fire damage.

— Rex

Thanks for all the helpful suggestions. This is where I'm at now. I contacted a Zion guide company for some direction:

Hello. The near record-breaking snow here in Northern Minnesota has me having to make last minute plans regarding my thru hike of the Superior Hiking Trail from May 3rd until about…..maybe three weeks later. I think I need to head SW for my May hiking/backpacking adventure. This has led me to your company.

I am looking to do multi-day backcountry hiking of Zion, but I do not know what the logistics would be. I would even be happy to do base-camping with several hours of out & back hiking to get myself in shape prior to taking on some of the more strenuous multi-day hikes. I have all the gear a person needs, but no experience hiking canyons or through deserts.

Would it be possible to get backcountry permits at this late juncture? How about the ability to set up a base camp within, or very near the park? I will have an AWD vehicle, though it's a sedan. Would your company be able to create an itinerary for me that would satisfy what I'm asking for here? If so, I would like part of that itinerary to include the guided Needles hike.

I'm very open to suggestions, as I know very little about the region. I do have quite a lot of backpacking experience, however. This being the case, I am aware that EVERY ounce in my pack adds up quickly and I've accumulated the gear that allows me to hike without carrying too much weight. This being said, I recognize the amount of water I'd have to carry during a backcountry hike through the SW is much more than I am used to, but I'd manage.

Sincerely,

Elisa Umpierre