I'll throw my 2 cents in though I doubt my thoughts are even worth that.
I'd trade Fehervary and #8 for #6 without blinking. While he still looks 'solid', he hasn't taken the steps I'd need to see to be willing to pay him top 4 money as an RFA. He still may get there, but he isn't yet.
(That said, while I was typing this Langway made a great point about not trading off their active roster and weakening it. To an extent it depends on what kind of money Fehervary is looking for as an RFA.)
I don't really think Alexeyev and Fever are close comparisons as far as their value goes. AA, while he's promising, is still just that - an unknown quantity given his injury history and being Lavi'ed last year. Arizona should be asking for an additional moderate asset on top of him. Of course, if I'm the Caps, I'm reticent to include anything of 'real' value, better than a 3rd round pick or 'squint and maybe' prospect, but I think they'd still do it after some stage hemming and hawing.
All of the above also leads me to say - I'd be surprised if any of those are 'good enough' for Arizona. I'm not sure what value a middle pairing defenseman truly has to a team at their position. Although I don't follow them closely enough to know how far away they expect to be from competing for playoffs, so maybe Fever or Alexeyev could likely be a core piece when they're ready.
Iorio and Chesley ... I'm definitely suffering from prospectis here, but I think both of those guys show more promise than Fehervary's current performance. Of course, when he was a prospect in Hershey, many of us here had him as showing more promise than our current D at the time. (That whole, "A guy who may become a solid NHL piece is better than a guy who already is a solid NHL piece mindset.) yeah, it's dumb, I know it is. But it's still the thought. I'd grudgingly include Iorio if Arizona was sending back another 2nd or 3rd. I'm not confident that Iorio will be anything more than Alzner was - a real solid defensive d-man, but lacking offensive skills or foot speed to be truly good. More of a 'succeeding on name recognition and reputation' guy.
Since this has been a thing over the past few days ... I certainly wouldn't want to trade any future firsts just to move up in the draft (unless it's to #1/#2, but that won't happen). But if they did have to trade a future first, I'd need it to have lottery protection in as close to perpetuity as possible. This team, as it looks right now, certainly doesn't look likely to place high enough to avoid the lottery.
And Miro is completely off the table for me in this kind of a deal.