We just completed an initial 14-team dynasty draft which included rookies. The top 14 rookies (which would be 1st round rookie picks if held separately) went as follows:
1.03 (#3 overall)
3.07 (35)
3.14 (42)
4.01 (43)
4.04 (46)
4.12 (54)
8.01 (99)
9.01 (113)
9.02 (114)
9.07 (119)
9.14 (126)
10.01 (127)
10.07 (133)
10.10 (136)
Making a really rough assumption that this is a typical year (just because I don't want to think any harder than that) and another rough assumption that you will have an equal chance of getting each 2007 draft slot, the average of the above 14 picks is pick 85, or pick 7.01. In a 12-team league, the average of the first 12 picks above is about pick 77, or pick 7.05.
So, let's say that if we're talking about 2006 and the above draft is typical, the "average" 1st round rookie pick is worth a mid 7th rounder in an initial dynasty draft. Let's say pick value is akin to monetary value. What's the discount factor for delaying a year? Do you expect a 10% rate? 20%? 30%? 50% even? The importance placed on now vs. later varies a good deal among people, and has to do with drafting style / player mix in the initial dynasty draft you are having, but the fact is the pick dropoff is a lot less than people think even at high discount rates. I'll illustrate.
I go to the FBG pick value calculator and find that pick 77 (7.05) is worth 341 points. The pick which is worth 20% less is pick 84, at 284 points (341 / 1.2 = 284). Pick 84 in a 12-teamer is pick 7.12. That's just 7 spots lower than the pick is worth in 2006. At a 30% discount, we're looking at pick 87 or 8.03, just 10 picks later than the comparable 2006 pick. Even a 50% discount from this year's pick 77 is right about pick 92 or 8.08, not much more than a round worse than the 2006 value.
This tells me that the average 2007 1st round rookie pick, without knowing what slot it will be in next year, and assuming the draft I was just in was typical, is worth somewhere around and early- to mid-8th round 2006 initial dynasty pick today.