Located on Rattlesnake Mountain on the former site of the old Snoqualmie Winery, this spot is now called Snoqualmie Point Park. On my last visit in early 2007, they were doing heavy-duty construction up there...pulling up and moving earth, laying concrete foundations, laying sod, etc...Great, so natural! The Park has since been completed and it looks nice. It's certainly more useful to the local community, but it's just not that Twin Peaksy anymore.
Unfortunately, this location will probably never look or feel the same as it did in Twin Peaks. So it goes. Since the landscape up there has been altered so much, it's very difficult to locate the exact spots where they filmed. I recommend taking screen captures of the scenes with you, then lining up the mountains in the background.