1. Since they will not be able to include Florida's electoral votes even if they win the state, that puts at a major disadvantage to their Democratic counterparts. To make that up they would need to win every other swing state and I see that as a long shot.
2. Politicians have ego. Senator Rubio is ambitious and I cannot see him choosing to be Vice President to a, quite frankly, lesser politician in Allen West.
With regards to Herman Cain, I do not see what is so impressive about him. It seems that all he does is repeat the standard conservative talking points of the last 30 years, while offering no actual new ideas. Maybe one of his fans can help me out with that.