I like Hudson but really really dislike Heath, so I guess that pair is out. Also, I'd swap middles to Hudson James and Heath Allen to avoid a combo with both names ending in -n.
Colton Allen and Connor James feel like I'd get their names mixed up too much. I know they are all alliteration, but these seem more tongue-twister-y than the other pairs. Also, I'd swap middles again to Colton James and Connor Allen. Same reason as above.
So I guess my pick is Denver Allen and Dakota James. I kinda like Denver (we considered Denver Andreas for our second) and am indifferent to Dakota. So that's the winner!
Alexis and Alyssa are out immediately, as they are just way too close in sound. Also, Alyssa Celeste has a LOT of S sounds!
I would choose Sophia Grace ad Sadie Faith, because I like the names Sophia and Sadie. I'd be really sad about the matchy middle names though. :) And how 'ordinary' Sophia Grace sounds.
Three boys nappin', one mama namenerdin'
To peruse my top 100ish names:
http://www.behindthename.com/pnl/82589To peruse my non-name musings:
http://jodifriesen.blogspot.ca/