Really keen to swords .. with marines ...
Well it's doable but you're gonna have some trouble getting it working.
A neat idea. The main problem is that vanguard vets are very expensive, and assault termies are hit or miss. Just for kicks, how about this - switch out the captain for a librarian, put him in termie armor with a SS. That's 140 points, not much more than the captain, and he comes with a sword so it's still fluffy. In 500 this puts you 10 points over, but if you don't mind dropping a tac squad sword it's not a big deal. That ups your mobility in small games a TON, b/c of Gate of Infinity. It's my personal choice, since I play eldar and being where my opponent doesn't like me is kinda my thing.
SM bikes have always under-whelmed me for their points cost. You already have bolters in the form of tactical marines, do you really need more mobile bolters?
This is probably a result of me being to used to fire dragons and banshees and the like, but I enjoy it when my units have a specific purpose. So if you have points to fill up, I ask myself "what does this army need".
Honestly, don't rely on internet folks to decide that for you. GO OUT and play a few games, and you'll see where you're lacking.