A lot of great suggestions here! One thing I thought I'd add, when we go on trips with our Chis I always bring the front pack carrier. That way, if your taking a long hike and their little legs get tired, they can hitch a ride with you. I have two so Bella and Wiley take turns in the carrier and on the harness. Despite being bigger then Wiley, Bella seems to especially love the carrier (it's like a baby carrier that you can hook them into but they can still look out of that you carry on your front, it's very comfy too, I can go see what the brand is if you want but I just got it at Petsmart for about $25), I suspect she just likes being carried by mama though!
Also, make sure he/she is up to date on shots, worming, flea and heartworm meds first too! Don't want your baby getting sick! Have fun! We are taking Bella, Wiley and Chloe (my Lab) on a day trip out to an island on the lake this weekend and silly as it sounds I prepare them just like I would for a baby, snacks, kennel, tie out stake, life preservers (yes, I'm anal) for my Chis, Chloe being a lab doesn't need one, just a firm word that enough is enough when she gets tired swimming - she's older, 5 1/2 and listens well despite being discouraged that she I wont let her swim herself into exhaustion, lots of water to drink and toys etc... sweaters in case it gets cold and the doggy pack goes everywhere with me! Have fun!