[mthoms]

I have a similar idea (currently on the backburner) but instead of focusing on "peak" season I thought you would define your own criteria. Some examples:

1. When is a good time to visit (ski resort) based on your chances of catching a powder day? What about a sunny day? What about no lines? What about all 3?

2. When is the best time to visit northern Thailand when it's not too hot.. but air quality is still decent (ie not peak "burning season")?

3. When is a good time to visit San Francisco if I'm into music (perhaps during a festival) but I can't stand rain? And how does that correlate to hotel pricing?

Etc..

[nxsynonym]

I like this approach a little bit better.

Only having "peak" and "off-peak" could have a waze-like effect, directing more people to "off-peak" might help distribute the demand surges a little, but probably not enough.

Being more specific and tailoring time frames to interest/objectives seems like a better approach.