First off, congrats on your twins. When are they due? I ask because my b-day is in Sept too. LOL...
Secondly, I searched until I was blue in the face looking at doubles & there is not a SBS in existence that takes 2 infant seats. Like Abby said, that would be one wide stroller.
Honestly, in the beginning the LOs don't seem to care much if they are SBS or not (at least mine don't). The double snap-n-go is a much better way to go. I couldn't survive w/ out mine. I know there are ppl that frown upon using the car seat in the stroller, but w/ 2 it's a PITA unbuckling one putting her in the stroller buckling her in getting her situated then repeating the process w/ #2. I know this because I gave it a shot yesterday w/ my Combi Counterpart Tandem because I hate my Flex Locs. Let me tell you, in 110 degree weather that was just too long & too uncomfy & then their seats were on fire. I'm happy to wait until they are out of their buckets to try that again.
Now, I too am on a mission to find myself a double jogger that I like because of this. My 2yo DS us flippin huge & wound up not fitting well in my Combi. I went w/ the tandem because it had the child tray for my 2yo but the footrest is too small & folds back. My 2yo figured that out quickly & will drag his feet. I need a jogger that will keep his feet off the ground.
If money is no object for you I agree w/ MSK & go for a City Mini by Baby Jogger. I drool over her stroller every time I see it.
If money is an object I've been hearing pretty good things about the in step safari jogger
http://www.instep.net/Product/Swive..._Suburban_Safari_2_Jogging_Stroller_11-AR800/
I tried out my DS & one of the girls in it at BRU the other day. I was pleased w/ it's ride even though the display stroller had flat wheels. LOL... My DS doesn't care for strollers much these days but he LOOOOVED being next to one of his sisters.
Also, like MSK said, don't be afraid to wear one if needed. I've done it a few times when I needed DS to be in the stroller & it works great. Great bonding w/ one of the babies & gives them a break from being in a seat or stroller.
I'm not sure how much help I was (if any) but it really is going to boil down to you needing to go try out strollers & see what works best. But there are no SBS that take 2 seats.