Answering your questions is nearly impossible to do... The answers depend on so many variables such as amount of traffic, size of websites, WP configuration, server configuration, MySQL configuration, PHP configuration, caching, etc, etc...
But what I can say is that it seems you are paying a lot of money... although I don't know the size of your site or the amount of traffic they get.
Personally I use LiquidWeb for all of my personal websites. I have lots of personal sites, some with lots of traffic and/or lots of data (files + DB). I only recently had to upgrade to a plan that costs me $250/month but that was because of a 'friend' of mine was using some space on my server and allowed it to get hammered with spam. I think if I had identified and fixed the issue before upgrading servers, I could have continued using the $204/month plan.
They have awesome support, have cPanel + WHM, and will work with you to tweak your server's configuration so that it is optimized for your needs.
I've been very, very happy with LW and have been with them for about 8 years or so. I would suggest looking at their reasonably priced dedicated server plans.
I've also heard good things about rackspace though I've never tried them.