Hi there
I'd try and narrow it down a bit before looking for an actual guidebook, at least to the general area, or a specific long distance route if that's your preference. There's lots of information on the internet, but this very website is one of the best places to start. Read some reports on anything you like the sound of, and it'll give you a good idea of the type of terrain.
Once you've narrowed it down a bit, Cicerone Press do some great guides.
A few possibles that spring to mind -
- Skye Trail (mixed walking, some fairly wild, on this wonderful island, without any technical difficulties on route, but very close to the best scrambling in Scotland)
- Affric-Kintail (a short-ish few days walking through beautiful glens)
- West Highland Way (rather popular but a good intro to Scotland, and with much more infrastructure than the others)
- part of the Cape Wrath Trail (the ultimate Scottish long distance walk, but not a marked trail as such, and passes through some quite wild country with few places to re-supply).
If you wanted to make up your own route, which I would definitely recommend as an option, some of the most dramatic areas suitable for experience hikers are; The Cairngorms, Torridon, Fisherfield, Knoydart, Kintail. There are many more. Walking in the Scottish hills normally requires a decent level of navigation, few trails are marked (some of the LDP are, some aren't), using map and compass work. Ordnance Survey maps are excellent quality and widely available. GPS/phone as a back up only would be my choice, often there is no phone signal in the wilder glens.
If by lodge, you mean hotel/b&b, most of these walks will have something at the ends or at key points, but you'll have to book well in advance if its a summer trip you're after. They won't in themselves be able to resupply you, and you'd want to check where the nearest supermarkets are, most larger villages would have a small one.
Gas canisters would be best sourced at the beginning of your trip. They are most common in what we call Outdoor Shops, one of the biggest is Tiso (a bit like REI) who have branches in the cities. Once in the wilds, it depends where you are really. Towns like Fort William and Ullapool will always have somewhere, smaller places maybe not, and supply chains have been a bit sporadic since Covid. We tend to have two types of isobutane canisters; screwfit general ones such as Primus, GoGas, Coleman, MSR, Jetboil which are likely what you are familiar with; and Campingaz which are blue ones with a specific fit that only work with Campingaz stoves.
To really see the best of Scotland, I would try to keep some flexibility in your planning, so as to adapt where you go to the forecast weather. Sometimes the west is bad when the east is good. Unfortunately it can change very quickly, but you'll probably be used to that in Washington state!
Finally, avoid the main summer months of late June to mid-September because of the scourge of the Scottish midge and, worse in some areas, people
If I could chose any "best" time to go, it would be now, Easter to mid-May, or maybe late Sept.
Enjoy your planning!