Email can be veddy, veddy efficient. Yet... email can also be veddy, veddy ineffient.
I've been trying to get together with a old friend for two weeks now. We have a very close, loving email relationship - but we've rarely talked on the phone ‘cause neither of us seems to be much good at it. We're both introverts and are much more comfy chatting thru our fingertips.
Problem is... we're trying to be oh-so-considerate with each other's time and schedule that we can't seem to get anything down on the calendar! You know what I mean...
Me: "So, are you busy next week? Wanna go get a drink? I'm free Tuesday, Wednesday and Friday."
My friend: "I'd love to see you - let me check my calendar and get back to you." (a few days go by)
My friend: " Sorry it took me so long to get back to you. Tuesday or Friday work for me - how about you?"
Me: "Oops - my Tuesday and Friday are booked. How's your schedule the next week? I'm wide open."
My friend (two days later): "Me, too, just pick a day."
Me: "How about Thursday?"
My friend: "Thursday is good, what time?"
Me: "How about 5:30? Or later - around 6:30?"
My friend: "Either way. Where would you like to meet?"
Me: "Doesn't matter - want me to come your direction?"
My friend: "I don't mind driving your way - whatever works for you."
Me: "Let's meet in your neighborhood - I haven't been there in a while. What's a good place to get a drink?"
Blah blah blah blah blah... this can go on forever, can't it?
So... what I'm learning (yeah, I'm a little slow) is to offer up a date, time and place REAL early in the "conversation."
Instead of all the back and forth, how ‘bout this?
Me: "Hey, are you busy next week? Wanna get a drink Tuesday or Wednesday?"
My friend: "Sounds great! Where should we meet?"
Me: "How about Finnigan's on Tuesday around 5:30?"
DONE.

p.s. this also works REALLY well with clients. Instead of trying to figure out what's convenient for both, just make a proposal. Chances are, it will work for your client and voila! You'll be on the calendar!
This happens to me all the time. It does work better to just state a date.