It is going to be very hot. I was staying in Pefkos end May and part of June, and it was very hot the second week. On the plus side, the sea will be very warm to swim in. A handy tip is two sunbeds and a brolly cost 8 euro a day to hire; but if you go to the beach after 4.30pm they don't charge so you could have a nice hour or two when it isn't so hot.
The Lindos acropolis is good to visit, but do it early in the morning say 9-10 am or later in the afternoon 3-4 pm. It isn't open on Mondays. Get a taxi from the rank in Pefkos for 8 euro each way (fixed price) which is the quickest and easiest way to get there, the early public buses are often full. Be prepared for it to be even hotter in Lindos than Pefkos. You can walk up through the streets to the acropolis.
There are one or two shops in the town that sell excursions, and also car hire places.
I can recommend a few restaurants:
Dama Dama which is down the beach road, lovely Greek food.
Philosophia is on a mini cliff above the beach, there are steps down to it may sometimes be closed in the evening if they are holding a wedding! Spectacular sunsets. Expensive but unusual menu.
Spitaki 'The Little House' one of the oldest restaurants in the village. If you like seafood try the Symi shrimps which come fried and headless, you just eat the whole shrimp as their shells are so soft!
Taverna Nikolas is on the outskirts but is also in a prime position for viewing the sunset. Gorgeous food with his fresh veg from his own allotment. Need to book if eating after 8pm as very popular, but by then you'll have missed the sunset anyway.
Terpsis on the main road through, opposite Spitaki, a more unusual menu, and divine desserts.
There are loads to choose from, including chinese and a fast food place, loads of bars which also do food and have play areas and the odd pool table and table hockey. Everywhere does kids menus and pizzas.
To get a map of the town, go to www.pefkosexclusive.co.uk and choose map. You can print it off and by clicking on the suitcases, cocktail glasses and knives and forks you can locate accommodation, bars and restaurants.
I should warn you that Pefkos has a few steep-ish hills, and and you will be at the top of the village, can be hard work in the heat. Are you staying at the aparthotel on Bakery Rd? That is one of them! However there are some pictures of the appts on the website. There is another Stella View appts on the Lindos Rd which is why I asked.