Hi and welcome!

I would just ask the taxi driver in resort for a price. I'm sure it would be cheaper than pre-booking.

i am going to athens in october and have been looking on trip advisor, most people suggest taking the metro, depending on where your hotel is as to which station you get off, its very cheap and very easy to do apparantly so that is what we will be doing, less than half the cost of a taxi i believe

if you're looking at pre-booked taxi transfers bear in mind the tour operators usually charge up to QUADRUPLE what the local price is,if you really want a taxi just go to the rank and join the queue. however if your hotel is near a metro stop just take that,it's really cheap to get into athens(airport is way outside of the city),most tourist hotels in the centre are no more than 5 minutes walk from the metro,or you could get the metro to the city and then a taxi direct to your hotel if you're not that up for navigating round the place on arrival! a taxi from spata into athens would be pretty pricey i imagine,never done it myself as i've always took the bus or metro and headed straight for faliro and piraeus. as for the economic situation,taxi prices have remained the same on Rhodes and other islands,theyre regulated by the government and all drivers will agree a price for you before you set off,and you can request a price guide from them at the ranks,they can and will add to the price if you've got lots of luggage and expect them to pick up other people if there's room!

13 days in Athens would be rather too long for us! As mentioned the Metro is the cheapest option although cabs are plentiful. If you pre-book I suppose you get a set price. Depending on arrival time the traffic can be grim and this journey by road could easily exceed 40 mins. If you are travelling to Crete by ferry you need a suburban train to Piraeus as the Metro stops short.

The Metro is cheap, €6 or €10 for 2 tickets, but the bus to Syntagma Square is even cheaper, €3.20. It runs 24/7 from right outside the terminal doors (far right).
A taxi would be around €40, more between midnight & 5am.
If you use either the metro or bus it is important to validate your ticket, on the bus this is a machine (orange box) on board, the metro you validate before you board.
The easiest mode of transpost depends on which hotel you're staying at.