If you're writing a story than starting with (relatively) bad designs and then improving them through experience is a good story in and of itself. As such when I role-play I never try to build optimized designs from the start.
Also in order to have good designs you need to know what you'll use them for. Are your ships supposed to operate alone or in groups? Are they to be specialized or not? Are they supposed to be a quick response vessels, attack ships or general purpose workhorses?
With that said, there are some problems with your designs. MarkAFK already posted one of those problems - the missiles speeds. Generally an offensive range over three hundred million kilometers is rarely required, unless you have certain, specific doctrine in mind. Not only that, but please remember the enemy ships may be moving away from you, which will cut the effective missile range. For example your Iron Heart missile is slower than your frigates and battlecruisers, which means those ships can just run away from your shipkillers. Entropy can catch them, but if Tennessee is moving directly away from them, the effective range is reduced to four hundred and thirteen million kilometers.
Second, if I read it correctly, the beam fire control on your ships is optimized for much greater tracking speeds than your turrets. For example Tennessee lasers can track at ten thousand kps (less than the speed of your ship, which completely defeats the point of turreting weapons) while your FC can track them at sixteen thousand kps. Either improve tracking speeds on your turrets or adjust fire controls.
Third, your ships have different speeds. If they are supposed to operate independently, that's fine, but if you intend them to operate in groups, then a lot of the speed is wasted. In such a case it would be best to adjust it, so all the ships have more or less than same speed. Again, that's only true if you want your different designs to operate in unison.
Fourth I'm not sure I would use passive sensors on PDCs - tracking stations are much better, although probably more expensive.
Other than that I'm not sure I would use vessels with only eight months of deployment time, but that's a personal preference.