Wait until late May to ask the question!
Why?  Plans and deals will probably change.  Also provide your area when
you do ask.
READING this group for a while will get you lots of info.

LB

Phones will have completely changed by June.  I would hang around this group
and listen until then.  Also check out www.howardforums.com and
www.phonescoop.com.  You actually can use New Every Two two after 22 months
(instead of your full contract term).  They want to lock you in before you
expire.

New every two is an awesome deal because not only do you get the 2 year
price on a phone (which is heavily subsidized) but you also get $100 off
that.

For your other phone, I am not 100% sure what the policy's are for upgrades
on the secondary lines in a family share plan.  Since they are less than
$39.99 (I think that is the required level) they don't fall under new every
two, but I think they may be eligable for some kind of handset discount
(like allowing you to buy at the 2 year purchase price, just without the
$100 off that).

Unless you think you are going to get rid of your cell phone in the next two
years or are displeased with the service I would not sacrifice the equipment
deals to be month to month.  I find Verizon's service to be excellent and am
not considering switching (and I manage 20 lines of service for our
company).  That said, things can always change (and frequently do!) in the
wireless industry.  It is very possible that Verizon may overload their
network due to rapid subscriber growth in your area and have service go down
the tubes.  Hopefully this does not happen, but you never know...

-Eric