This is an excellent question that you are likely to receive a wide range of answers for. However, my own personal feeling is that Bassanio is yet another character in Shakespeare's plays that shows himself completely unworthy of the wonderful, beautiful, intelligent and witty wife he ends up with. Let us just review what we know about Bassanio: depending on how you wish to stage his relationship with Antonio, he could be presented as callously manipulating Antonio into giving him more money after he wasted the rest of the money he had from him. Let us remember that it is this desire for money that leads Antonio to make his "merry bond" with Shylock in the first place.
In addition, don't forget how Bassanio talks about Portia when he reveals his plan to Antonio:
There is a lady richly left;
And she is fair and, fairer than that word,
Of wondrous virtues.
It is the wealth of Portia that is mentioned first, then her beauty and virtues. Given the way in which Bassanio has just admitted that he has wasted the money Antonio gave him before, it is hard not to assume that he cynically wants Portia for her wealth alone. Even though Bassanio manages to choose the correct casket, which perhaps indicates some good about his character, it is Portia, not Bassanio, that engineers the revenge against Shylock and the release of Antonio, and Bassanio is reduced to being a stand-in character during the court scene whilst his wife takes the stage. Bassanio can be said to be nothing but a weaker character when compared to his wife.
As explained in the answer above, Bassanio's suit to Poria wasn't ruled plainly by his love for Portia but more importantly it was his greed to accumulate more wealth since he had washed his hands off of his own assets. He borrows money from Antonio with the very intention to repay it with the fortune he might get his hands on after choosing the right casket. Even his choice of selecting the right casket wasn't genuinely due to his own merit, but it was the song playing the background which gave him a clue which casket was to be chosen. the last words of the first three lines of the song are "bred", "head", "nourished", all of them rhyming with "lead". Portia, here, does stray a bit off from her father's will by indirectly guiding him to the right choice of casket. In another scene, Bassanio gives the ring to Balthazar(Portia in disguise) though he promised her that he'd never to take it off, and taking it off would mean that "Bassanio's dead", but he doesnt abide by the promise he makes to his "virtuous" wife. Even the way the last scene ends, indicates that further problems might arise between the two and would make an unquiet home.