"Bob Hayden" > wrote in 1. How differently do I "cook"
> them to account for the size difference...maybe 8 hours instead of 6? 2.
> What about the flap on the bottom side...leave it or cut it off? 3. What
> about the whole top section that does not have he rib bone structure?
> Anything else I should do differently or be aware of?

Bob,
I've cooked both for many years and I've decided to stick with baby
backs or loin backs as they are often called. The spare ribs have much more
fat and meat on them and often they require a longer cooking time. In my
Backwoods smoker I figure 7 hours instead of the usual 5-1/2 to 6 hours for
baby backs. If you are making them for yourself (ie. not in competition)
then trim as little as possible. At $1.59 you probably bought untrimmed
spares. You can trim them into St. Louis style by cutting parallel to the
bone end starting at the longest rib if you want pretty rib. The big flap of
meat can be cut up for rib tips and onions with a dose of cayenne pepper.
There's no real difference in taste but the spares just have much more
fat. As far as price goes... we buy untrimmed spares for $1.29 at BJ's and
loin backs at $3.79 a pound. St. Louis trimmed spares at Albertson's go for
$4.99 a pound but they go on sale at $2.49 a pound once in a while. We
stocked up on the St. Louis spares last time and just used them up last
weekend. I'm cooking loin backs today with the charcoal method Jack Curry
mentioned (ibid).
Whatever you choose to cook you will find a wealth of information here.
Experiment... often.

Ricky