If the tenants agree to modify their existing lease, that's up to them.

I used a spreadsheet designed for analyzing large multifamily properties and modified it for the motel.

All mine follow this, with a modifier value for unique special features like certain lake front etc.. 

They would also allow you to modify the rental agreement with only 30 days notice.

Generally, these bulk buyers might offer to modify with a balance at, or slightly above/below current value, but not 1/3 of value.

You made a verbal offer to extend the lease you sent over to sign, if they are unwilling to sign the new lease they are under no obligation to do so but you don't have to modify the lease if you don't want to. 

These are spaces that go for around $1,000/mth modified gross and not as nice as your property, but still a nice small office building.

They are also very flexible and can be easily added on to, or interiors can be modified without compromising the integrity of the structure.

Does it logically translate to larger units, or does your idea of a deal need to be modified?

If they are MTM you are free to increase or modify their lease terms.