I would attempt to move the Pack n Play upstairs into his room. Try that for a while, and then begin transitioning him into his crib either at nap time or when you lay him down for the night before his first wake-up and see what happens!! Sleep issues are sooo tough-- so hang in there :)
As for "CIO," your child is old enough try it; it will just come down to your personal belief system around using that method. I personally am not a fan, but it has worked for a lot of moms out there -- so, to each their own!
And, to the mother who said she did "CIO" with her 3 month old, that is WAY too young... poor thing :( It is NOT RECOMMENDED FOR BABIES UNDER 6 MONTHS!!!
Ferber actually says the following about "CIO" in the preface of his newest edition, as he takes pains to clarify his often misunderstood position:
"Simply leaving a child in a crib to cry for long periods alone until he falls sleep, no matter how long it takes, is not an approach I approve of. On the contrary, many of the approaches I recommend are designed specifically to avoid unnecessary crying."
Ferber's "progressive waiting" technique actually encourages parents to frequently comfort their child during the sleep training process.
Best of luck Mommy!