hiking and backpacking
Both wilderness areas offer excellent hiking once the snow has melted. Key trailheads into the Pecos are at the Santa Fe Ski Basin on the west side and near Cowles on the southeast. Both can be crowded during mid-summer. Trailheads near the town of Truchas on the northwest side are somewhat less crowded, but there have been problems with vandalism of vehicles parked there. Trails lead not only to good campsites but also to most of the high peaks, which are generally hands-in-the-pockets walk-ups under good conditions. Lake Peak, just outside the wilderness, requires a little scrambling near the summit, with some exposure. If peak-bagging, make sure you're off the summits by 1 p.m. during summer months, as the Pecos is notoriously lightning-prone.
By far the most important trailheads into San Pedro Parks are near San Gregorio Lake on the south side, reached by a gravel road off rough State Road 126 between La Cueva and Cuba. To avoid the crowds, consider instead going in from the north side, but it's way out in the boonies and help will be slow in arriving if something goes wrong. The countryside at San Pedro Parks is very different from the Pecos, featuring open meadows and low, rolling hills rather than the peaks and valleys of the western Pecos and the high mesas of the eastern part. A consequence is that the trails can be soft and boggy pretty much year-round. Hiking boots are a good idea, simply to help keep your feet dry.
Most of the mountain lakes in both wildernesses including man-made San Gregorio Lake, as well as the Beatty's Cabin area of the Pecos, are off limits to camping owing to environmental stresses. Campsites along the streams, however, are abundant and generally satisfactory for the backpacker or horsepacker, as long as you camp at least 1/4 mile from the closed lakes and 200 feet from the stream itself. Puerto Nambé, a broad pass between Santa Fe Baldy and Lake Peak where the Winsor Trail reaches the ridgeline, can resemble a tent city on summer weekends.
fishing
Probably the best fishing in the forest is at popular San Gregorio Lake, reached by a short walk from the trailheads that continue on into San Pedro Parks. Don't expect to have it to yourself. There is also satisfactory fishing along the Pecos River near Cowles, but be careful of private property restrictions. Many of the smaller lakes and streams support small populations of trout that can make it worthwhile for a backpacker to carry in a collapsible rod, although you're not odds-on to catch much. Some of the lakes have been stocked with trout.