I suppose cruising speed would be the most significant. Depending on the route, it could vary greatly. One direction from my home takes me into cornfield territory. The other direction is residential/business, with lots of stops. Averaging each to include stops would not be a fair assessment...not that it matters much to me. I rarely ride in groups and never cared much about speed, except when a pretty girl was kicking my arse.

Total distance was always more important to me, for use in directions.

I finally upgraded to a Garmin 605 this year. I believe it has a feature to ignore speeds below a set amount, which makes sense to me. I'll probably use that to calculate time-to-arrival for some light touring, unless the unit can do that too.