WHEN to go into the hospital..That is the question!

Well now that Toomas Mom is here we are free and clear to head to Labor and Delivery whenever our heart desires!!!!! So now the question is...even with this being my fourth baby.. WHEN? Do I wait until I've had 1 hour, 2 hours, 4 hours of consistent and painful contractions? It is such a tough call to know WHEN the time is right. Currently it is 1:40 a.m. and I'm up timing contractions. This isn't the first night I've done this so I'm not getting my hopes up too high. Sometimes they last an hour, sometimes 15 minutes. Sometimes they are 3 min apart for 45 minutes...then they die down to every 5-6 a minutes only to disappear completely. I'm REALLY not wanting to deliver at home or in the car so I definately want to make it to the hospital in good time, but I am still baffled by the WHEN I should go. With Erik's labor I was only at the hospital for a bit over an hour. I didn't wait around too long to go to the hospital either, it was just a really fast labor. Generally the rule is that each subsequent labor gets shorter, this was not the case with Kaitlyn. My labor with Kaitlyn was a bit over 4 hours at the hospital. I suppose when it is REALLY the time I will know, right? Or will I?!? At any rate Evan will arrive shortly...be it a day, 3 days or a week....or tonight (well probabally not but one can dream!)