The Ptarmigan Traverse is an absolutely classic and must-do experience at least once for anyone who’s into mountaineering in Washington state. Some high-level details:

• Technical skillset: In its simplest version, as just a through-traverse (e.g., not yet considering side trips to summit nearby peaks), it can be done with only a “Mountaineers Basic” skill-set: the technical challenges are basic glacier travel and scrambling, and the trip is otherwise essentially backpacking-for-mountaineers.
• Time commitment: While this route has been trail-run in insanely fast times, if this is your first time on it, I’d recommend allocating something more in the ballpark of a 6 or 7-day schedule.
• A car-shuttle is required, which (from Seattle) means nearly 6 hours of driving prior to the boots-on trailhead at the beginning, and nearly 6 hours of driving after the boots-off trailhead at the end. Two cars are required, and each must display a Northwest Forest Pass (or an America the Beautiful Pass).
• Permits: Somewhat astoundingly, this route doesn’t require any camping permits (yet… I imagine some day in the future it will.) What an incredible gift from nature this place is in the first place, and what a privilege it is that we are currently able to recreate there without the hassle of a permit system being needed yet. Popularity is only increasing, and it is crucially important that we each do our part to care for and preserve the land here by doing everything we can to minimize the way our presence impacts it: avoid killing the struggling alpine plants by–as much as possible–avoiding going off-trail and stepping on them, or setting up tents on top of plants, or peeing on plants (which will make a mountain goat eventually dig at that spot, shredding a square foot or so.) Store food appropriately (large Ursacks are ideal) to avoid habituating wildlife, which could lead to area-closures, and you don’t want to be “that guy” that ruins it for everyone else. And practice good backcountry bathroom etiquette (more on that below, but in short: at least pack out your used toilet paper!!) Be thoughtful and continuous towards the land, keep the area just as beautiful for the people who will come after you; and don’t do anything that would hasten or become a reason why a permit system would need to be established.
• The prime time of year to aim for is likely early to mid-July (for the best chances of stable sunny weather, but also crevasses not having opened much yet.) Consider avoiding a schedule that incorporates the July 4th holiday, though, as it is likely that a lot of other people will have the same idea, and many of the camps along the route are limited in space.
• An alternative to the Ptarmigan Traverse: For a similar trip in many ways, another option is the Bacon-Hagan-Blum Traverse, detailed in this video: https://www.youtube.com/watch?v=06M05mRV5pc&ab_channel=TheMountaineers It’s not quite as classic as Ptarmigan, but it is also an outstanding trip of its own, and would be significantly less crowded, even if scheduled over a national holiday.