You have two options with Vulture Peak. First option is a quick workout hike up to the saddle. This is a 0.8 mile 800 foot elevation gain. Your second option is to start from the back trailhead. This tacks on 1.4 miles each direction and a beautiful stroll in and out of washes up to the second trailhead at the base of the mountain.
From the lower passenger car accessible trailhead, the trail begins flat and wide. In a couple hundred yards you drop into an unnamed wash and then promptly climb back out. At this point my sister and I started to feel our lunch of Filibertos. It's not a good idea to eat greasy Mexican food before you hike. Anyway, from here you travel over a couple hills and through the bottom of a wash before you hit the upper trailhead. The trail is extremely easy to follow as it is well marked with very large cairns the entire time at the bottom of the wash. Once you leave the wash, the road to the upper trailhead is visible and you reach the parking lot in about a minute. From the upper trailhead (only accessible with a 4wd vehicle) you will begin your ascent. Actually, you've already climbed 200 feet, but you can't really feel it. For some reason, the first stretch of trail from the upper trailhead was the most difficult part of the hike for me. It is not a very steep grade, but it is relentless, and the ground was very soft and muddy from the previous night's storm. It's not long before the real climb begins, though. Once the trail really starts to go up, you gain elevation very quickly through a series of tight switchbacks that become steeper and tighter until you reach the saddle. I would say this is about a 700 foot climb in .6 miles. Since it was so wet this particular day, there were several spots of water trickling off of the boulders above the trail into small pools on the ground during the portion just below the saddle. At the saddle, you get great views of the back of the White Tanks to the east, and views of, well, I don't really know to the west. It's a good view, though.
The actual summit of Vulture Peak will be to your left when you are looking towards the White Tanks. It's tempting... The trail to the top is not maintained and is very STEEP. Like, hand over foot type. It sure is fun, though. Just make sure that you can get back down anything you go up. The route to the top is pretty straight-forward. You basically follow the narrow gully up. At one point you have the option of going straight or veering off to the right (It sounds vague, but you'll know). We chose to go right because it looked less steep. It worked very well, but I'm sure either direction is fine. At the top you get wonderful views all around. I didn't know anything to the south or west, but the Bradshaws, White tanks, Estrellas, Vulture Mountains, and Hieroglyphic Mountains dominated the other directions. There is a geo-cache with a logbook and some random other stuff that's pretty fun to look through. Stay up and enjoy the views for a while, but make sure to head down before it gets dark. Footing is fairly tricky and some of the rocks are loose, so you want plenty of light to get back to the saddle. It's only a couple of hundred vertical feet though, so it only takes about 10 minutes. The hike from the saddle back to either trailhead also takes no time at all. At your car, look back at the mountain you just climbed. That was easy! Really, though, it is easier than it looks.
To hike From Phoenix, take the 60 (Grand Ave) west to Wickenburg. Just shy of Wickenburg, stop at the rest stop and take a look at the Hassayampa River, which is pretty much perennial at this point. Once in Wickenburg, veer left onto the 60 at the intersection of the 60 and 93. The 93 will take you north to Prescott. Continue about 2.5 miles on the 60 (over the Hassayampa, which is usually dry at this point) until you reach Vulture Mine Rd, which will be a stoplight. Turn left and follow 6.7 miles to the turnoff for the Vulture Peak Trail, which will be marked well going either direction. Follow the well maintained dirt road through the parking lot about a half mile to the trailhead. If you have a 4wd vehicle, follow the dirt road an additional 1.4 miles to the upper trailhead. The lower trailhead is accessible by any passenger car.
WARNING! Hiking and outdoor related sports can be dangerous. Be responsible and prepare for the trip. Study the area you are entering and plan accordingly. Dress for the current and unexpected weather changes. Take plenty of water. Never go alone. Make an itinerary with your plan(s), route(s), destination(s) and expected return time. Give your itinerary to trusted family and/or friends.