re: Yellowstone National Park:

Worked there one summer as a college kid. Strongly suggest going in early summer or late summer. Crowds turn the main roads into parking lots during peak season. Call & ask for the best dates to beat the crowds. Stop and ask any park employee, preferably the student aged ones, where they go on their off days, as they know where the best places are & where not to go with regards to crowds.For instance, to watch Old Faithful, avoid the huge crowds sitting on benches like school kids & ask for directions to the trail up the nearest mountain. Hike up a relatively easy trail & at a rest stop, enjoy the gorgeous scenery in almost complete privacy, absent a few student workers probably. Bring your own booze. The stores there are pricy but admittedly, convenient. Get up early each morning to again beat any crowds. Do not leave trash out by your tent: bears like easy food. Fact.