This is actually for my daughter who will be going on her honeymoon in September. Her father gave her $ for accommodations to spend in Greece. She has her hotels in Crete and Athens booked and her remaining budget to play with is $1200. She needs to find a way to split that between Santorini (3 nights 9/13, 14, 15) and Milos (3 nights 16, 17, 18). She's running into 2 problems: A) Of course Santorini is expensive but it's her honeymoon right? They don't intend to rent a car, just take it easy on the Caldera. B) Milos is raved about as secluded/less touristy but the accommodations are mostly booked. Seems like there are so few options here.

Any recommendations?

MIlos can be difficult without a car.... its bus network/schedule is limited even in high season, and by mid-september may be skewed to serving the school children.... Milos has many beaches, but not easy to access them without a car. Tell her don't fall in love with a place just because it's "raved about" -- by whom? someone she knows? Has she questioned them in detail about it? I've been there 3 x but know of some other places that may suiti her better. Has she looked at Folegandros??? it has THE most beautiful Chora (high town) of any of the Cyclades islands, In my opinion (and I've been to about 15 of them) ... and here's a fab hotel https://www.anemousahotel.gr/en/article.php?cat=2 with decent rates, in Chora. THere is bus service to several nice beachs, too, and Folegandros ha frequent ferries from Santorini, only an hour's sail.

I didn't comment on Santorini ... I always recommend FIROSTEFANI for several reasons, It's right at the Northern fringe of the Main towon (FIRA)< but out of the hubbub, it has plenty oof hotels with rooms right on the Famous Caldera View ... but at half the price of hotels in the "overfamous" village of OIA What's more, one can do without a car, just walk down the rimside path to the attractions of FIra Town - shopping cafes, museums, nightlife, then walk back late evening to serene Firostefani. ONe can take a bus to OIA ===Tip - go VERY early in AM - 8 - 8:30, to walk arouond in peace; at 10 AM or so, huuuge crowds invade from cruise ships... even in Sept, and the lanes are jampacked with people. That's when you hop back on the bus & go explore elsewhere. If one stays in Firostephani, there are also lovely places for dinner with a sunset view (such at Remvi Cafe) that don't cost an arm & a leg.

Some Firostefani caldera-view hotels I've sent people to, that they enjoyed, were Agnadema Apartments (has pool), Blue Dolphins (a great value), Sunset Hotel, Villa Ilias. Mill Houses & Dana Villa may be above their budget, This link https://www.booking.com/city/gr/firostefani.html lets you browse availability & price & if you see somethin you like u can contact them direct if you wish. TIP: when you put in your info/dates, a list of hotels willlpop up, but do NOT click on those. = instead click upper RH ikon "show on Map" and all hotels will appear as blue balloons, with EXACT locations Each balloon will show price for 3 nights & if you see a good price, click & get photos & details

Here's what booking dot com has to offer for Santorini, Sept 13-16 for $200/night: https://tinyurl.com/3np7rf6s
You can easily adjust this amount if you choose less-expensive accommodations on Milos.

We stayed at Blue Dolphins as recommended by Travelerjan, and we loved our stay there. Price was $230 per night for a very nice room with a deck overlooking the caldera. For an extra 25 euros for two people, you can have a delicious huge breakfast delivered to your room, and eat breakfast on your deck! It was heaven!