NEWS FLASH
The former operator of Zagreb Airport, Zračna Luka Zagreb - ZLZ (not to be confused the with the current operator Medjunarodna Zračna Luka Zagreb - MZLZ), plans to build a hotel directly across from the new passenger terminal in the Croatian capital. The 32.000 square metre four-star hotel will feature 150 rooms, with the operator planning to meet airline requirements in order for the facility to be able to offer accommodation for cabin crew staying in Zagreb overnight. ZLZ has requested a location permit for the hotel (a pre-requisite to a building permit) to be issued by authorities. The operator will then offer an international hotel chain to run and manage the facility for a set period of time.

Comments
However yes, this new 4* airport hotel was planned and designs exist to blend in with the current terminal, Initially it'll have 150 rooms and suits and this can be easily expanded to 250 rooms and suits.
There's a need for more hotels in Zagreb as number of visitors visiting Zagreb grows 11% yoy basis since 2010.
Hotel Aristos is next to the airport, http://www.hotel-aristos.hr/en/
And hotel Stella http://www.hotel-aristos.hr/en/ is near the airport too, about 5 min drive or 10 min walk from the old terminal. Aristos is 4* and Stella 3* hotel.
It was a 6 minute drive but walking would be 20-25. I am sure a taxi would not have been more then 25Kuna ( $4 USD)
https://drive.google.com/file/d/0B53P1dZ8EIXJR3JQTmw0a1ViRFk/view?usp=drivesdk
82USD per night.....my friend, you just got robbed.
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It is a matter of perspective.
I am fortunate enough to consider $82 USD as being cheap. Maybe it is expensive for you, but for others who have the means and look for location, it is a good deal.
I am fortunate that I can value location more and not worry about getting value for cost.
There are two smaller hotels right at the old terminal 20 and 12 rooms, clean, nice rooms up to 3* standard however they charge only 250 kuna per night, B&B included.
ZLZ Hotel most likely it'll be either Marriott, Sheraton or Hilton 4* hotels, as these chains are already in Croatia/Zagreb. However don't think they'll dare to charge more than $80 per night, this indeed seems very steep for a 3* hotel, Stella seems overpriced. Was it fully booked out, why was it so expensive normally prices for a 3* hotel in Zagreb are around 250-320 kuna, that around 3750-4800 Serbian Dinars, or 40 to 50$ per night.
4* hotels tend to be bit more expensive around 500-550 Kuna - $70-85 per night.
5* Hotels tend to be around 750-1000 kuna depending on hotel, $110-152 but there are only 3 soon five 5* hotels in Zagreb.
Sheraton, Westin, Esplanade. Intercontinental and Kempnski are is looking for locations in central Zagreb, for 250-300 room hotels. Zagreb Chamber of Commerce was mentioning something about it.
Currently Zagreb has around twenty 4* hotels and around 30 3* hotels.
Loads of hostels, around 50. Place is becoming popular city brake destination with 1.25 million visitors expected this year (conservative estimates).