I am currently using Visitlead.com - and it's quite nice.
It's not so common yet, since it came out recently, but i think it has some really cool features. What i especially like about it is that you are not limited to livechat, instead you have several options to interact with your visitors...
I'll quickly go through your requirements. But many of the features I'll talk about are also described on their homepage - probably a bit better! ;) --> Visitlead
Reports on how many chats we receive daily
No problem there. That's showed on the dashboard.
Reports on what time of the day we receive the most chats
I'm not sure if this feature is available, but i guess even if it is not you could just ask your operators when they have many chats...? If this does not work you could also use a 11th operator as a kind of a 'emergency operator' - if this one gets visitors, you know that all others are highly occupied. :)
Reports on what pages the customer visited
You have a detailed history about that, for every single visitor and how long he was on every site. You even see if he is 'active' on your site or has another tab open!
We have 10 CS Reps that need to be chat operators
That won't be an issue. We also work with a bunch of and never had any problems.
We need to be able to see what page the customer is looking at (URL)
Now we get to the interesting points. Actually, you do not only see the URL, you can also watch the visitor's view. Co-Browsing is a really cool thing when you tried it once!
Customized chat windows (Embedded, invite windows, scrolling windows)
Yes again! There are already some Templates you can work with, but you can edit them as you wish or also can create completely new ones.
Allowed to set offer windows on certain products if the customer visits them
You can do that as well with widgets. You can create as many of them as you wish, completely different or whatever.