As people've already said, VP must be selected with a few things in mind :
1) He needs to appeal to a block that Ron doesn't already have & thereby bring in more votes
2) He needs to be someone who can carry the torch of liberty & set himself as the top contender for presidency in 2016.
The next one is probably is more crucial for older presidential candidates like Ron than younger ones like Obama I guess -
3) Since Ron is so old, a lot of voters will likely fear he might die before completing his term so his VP needs to be someone who, in people's eyes, is almost as good as president in terms of policies as well as has the strength to do the job if needed & for obvious reasons, MUST be somewhat younger (so Williams, Buchanan, etc are out).
Ron has three options in terms of how he can go about choosing his VP :
1) He can go for a libertarian or an independent who does NOT bring him a significant amount of new votes which may or mayn't please his main support-blocks but the bottomline is that Ron only has the smaller blocks like Repub-Libertarians, Independents & a few Dems but as a Repub, it'd be NEAR IMPOSSIBLE for him to get the GOP nomination WITHOUT the neo-con vote & they just won't choose an anti-war candidate & convincing them against war is an EVEN HARDER task in most cases.
2) To attract the neo-con vote, Ron can choose a neo-con VP like Palin, Cain, etc who're part of the establishment but that may turn off a lot of his main blocks because :
a) they might think he's sold out &/or this was the plan all along
b) if they fear Ron might die before completing the term then those supporting Ron because for his policies definitely WON'T want an establishment neo-con in charge
3) He can choose Rand & because he's not seen as part of the GOP establishment & his stance on militarism isn't as aggressive as some so he'll help Ron secure a fair chunk of the neo-con vote WITHOUT discrediting himself or losing a significant amount of his libertarian, inde & dem votes
I know media may attack the whole family thing but as I've said Ron NEEDS the neo-con vote to secure the nomination & choosing establishment neo-cons just discredits him so a cost-benefit analysis should yield that without Rand he can't get the neo-con vote while any other neo-con will scare away a fair chunk of Ron's own voters. I may be wrong but I think Rand is Ron's best chance based on how things stand for the moment so he should declare him as his VP candidate & let Rand pack in a chunk of neo-con votes, apparently he's a better speaker too if I may add.
Not to mention, only Rand has significant national appeal among those who've been talked about for VP & he'll likely be the only one who can be a strong presidential candidate for 2016 so he'll be able to carry the torch of liberty. Obviously, he's not so libertarian but much better than most neo-cons & neo-libs & agrees with libertarianism on most things like free markets, individual liberty, anti-socialism, sound money, etc so he still keeps most libertarians interested.