I've tried both viagra and cialis. I live in San Diego and used to go to mexico quite often to party. I took a viagra and ecstasy and fucked my girlfriend for what seemed like forever. It was awesome.

I've also used them when going to swing parties. It helps if you are going to fuck 3 or 4 girls in one night.

If it's just you and your old lady it is kind of overkill. I found that Viagra which is only supposed to work for 4 hours lasts much longer. Probably because I don't have any natural problems. She probably doesn't want you to have a boner for 24 hours anyway.