Obviously there's all sorts of combos that could theoretically work... (Lee + a pick, Sully + Amir + a pick, etc...)
Our offer shouldn't exceed the following:
Jerebko, Zeller, Sully, Young (or Hunter), the Dallas 1st and Boston's 1st for Horford
Why?
Jerebko - 5 mil expiring. If the plan is the sign another max guy this summer, Jerebko is gone.
Sully - Restricted free agent. If the plan is to sign another max guy this summer, we'd renounce Sully
Zeller - restricted free agent. If the plan is to sign another max guy this summer, we'd renounce Zeller
Young or Hunter - Throw them a prospect
Boston 1st and Dallas 1st - late lotto at best... not worth a ton. We're also going to struggle to find roster spots for those picks and the rookie contracts eat into our ability to add another max guy.
Anything more than that, I'd be uncomfortable. Horford would be a big get and really put us in position to go really hard at Durant this Summer, but Horford is also a 30 year old unrestricted free agent who is either going to end up bailing on us for nothing or forcing us to overpay him max money on a contract that gets progressively worse each year.
If the Hawks want a haul, that's my offer. They could keep Sully and Zeller if they want since they'd have the right to match any offer either gets in free agency.
That's a lot more than what Boston got for Rondo prior to his free agency last year (Crowder, Wright, Nelson, Dallas 1st and 2nd).