Agreed. I actually prefer to separate them out into separate lists, rather than try to affix a priority to them. Even though they aren't explicitly labeled as Someday/Maybe, all of these lists are subcategories of it:
Maybe Buy
Books to read/buy (and possibly sub-lists like fiction, work-related, history, etc.)
Gifts for ____ (sig other, kids, etc.)
Vacation possibilities
Future House Projects
Key People
Charities (new ones to contribute to)
Movies to see/rent
Next time in _____ (cities, countries to visit)
These I don't need to review every week. Maybe once a month, or every couple of months. Sort of the same concept as prioritizing them, but (I think) more effective because it groups them by context rather than priority. I'd have a hard time comparing priorities between a book I want to read and a place I want to visit. When I'm getting low on books, or want to be inspired by it, they're all in one place. When it's time for a vacation, those thoughts are all in one place. When it's time to start another significant home-improvement project, they're all in one place. Plus I've always found that priorities are so fluid that trying to keep them straight is more trouble than it's worth.
One other thing: Some SD/M projects are pretty unique, so they don't fit neatly onto a list with anything else. Example: I've had something on my SD/M list (the one I review every week) for over a year. I finally got sick of seeing it during every review, so I asked myself when it was realistic to try to decide to take it on. I wrote a note, dropped it in my tickler for 4 months from now, and took it off my list. I'll get to it again, and when I do, I'll either tickle it again, put it on my SD/M list, or decide to take it on as a project.