When I'm searching for airfare online, changing the days I fly in and
out on changes the rate dramatically.  Some sites will give rates on
their "ideal" days to fly on, but usually the dates aren't comvenient.

I find myself trying to manage lots and lots of searches as I search
each combination of days I'd like to fly on on each site.   It would
be easier if there was a different view that showed the lowest
available price for each departure date/return date combination.

Is there a better/easier way for me to find the best flight option?

The best site you'll find for this is Orbitz
www.orbitz.com

Below where you can enter what airports/cities you will be flying in,
there is a link for "Find low fares for weekends and flexible trips". 
Click on that link and there are several options for flexible dates.
My favorite search is a 30 day search for a multi-day (you specify
approximately how many days you want to be there) trip.  Orbitz will
then spit out an easy to read chart of the prices for leaving and
returning on every possible day.  Simply pick a cheap ticket that
accomidates your needs and you're set.

Just looked at this for flights... and www.orbitz.com is great.  It
has exactly the feature I requested.  Unfortunately it doesn't get all
the flights, I did another search on travel.yahoo.com and found more
flight time options at basically the same price as what I found at
orbitz.  But orbitz did a much better job of finding the day I should
be traveling on.

An interesting note in all this.  I've also learned that there are
optimal days in which to buy tickets.  Apparently University of
Washington had a research project and posted a web article that listed
the best days of the year to buy airline tickets.

Hi bacher-ga,
If you want to search multiple site for cheap flights the you should
try www.ufly4less.com Ufly4less searches & displays prices for up to
about 4 months ahead. You dont have to select the depart & return date
just select a period that you could teavel.

Blurb from the www.ufly4less.com site below

Ufly4less is a unique budget airline search engine that will always
find you the lowest price flights on Easyjet, Ryanair, BMIbaby, Flybe,
Jet2, ThomsonFly, MyTravelLte, EUJet, First Choice, Monarch and Are
Arann.

HTH

PS. They have a free trial download at www.ufly4less.com

The problem with asking for multiple days for departure and return is that it 
multiplies the number of possibilities that the computer has to
search. If for example a specific departure and return date displays
lets say 70 options but then you can leave on 20 days and return on 5
days there are now a total of
7000 combinations! (which the computer must extract and sort by lowest
to highest fare)

I have as yet to load ufly4less (the number of airlines it access appears
rather limited)

Orbitz only applies to flights originating in the US.

Personally I recommend MOBISSIMO.COM as by far the best search site.
Mongolia