We went to Sri Lanka this year. I haven’t used a Travel Agency for years - I’ve never not been able to cost out a nicer holiday for a lot less money - it’s does all involve time and research though if you’re going to do it properly!
Start with what time of year you want to go - our summer is their monsoon. We went in April - it was just warming up for their rainy season but overall really good weather. The East Coast is fine in our summer but the rest of the country is wet. Most of the places we wanted to go were on the Western side.
In terms of where to go - Lonely Planet in-line have a number of suggested itineraries of where you should visit based on your interests but also take a look at the Sri Lankan travel itineraries that more adventurous holiday companies like Audley, Exodus & Intrepid have and rip them off!
We usually do 3-4 days in each place - in Sri Lanka we had a day in Colombo just to get over the jet lag - we stayed in the Cinnamon Red booked on booking.com which does offer protection) before being driven to Kandy (there is also a train that is popular but DH wasn’t keen). I liked Kandy, it’s big and sprawling and not everyone likes it but it’s pretty magical around the lake at sunset with the view of the temple, monks and prayers on loudspeakers in the trees. We stayed at the Ozo (again from booking.com). We did days out to Sigiriya, Dambulla, Minneriya National Park (DD loved the Safari and seeing wild elephants) and Nuwara Eliya. We then got driven down to the coast and had 5 lovely days in Tangalle on the beach (staying at the Lagoon Paradise).
I used 2 different transports companies and found them on Tripadvisor (I contacted the Top 5 recommended companies, gave them our itinerary and asked for quotes). We had great drivers with both companies who drive carefully, spoke good English & had good new (ish) vehicles. Hiring a driver is very common and most Western families we met had done exactly that. If you want their details, happy to provide & recommend ours.
I go on Tripadvisor recommendations for hotels. They don’t cost a fortune in Sri Lanka and the basic local hotels (we had to stop for toilet breaks at 2) were really grim so I personally wouldn’t go less than 4 star. Food is good, varied and cheap (I’m veggie & had no problems). We met some Aussies who were using Air BnB accommodation across the country and were having a really mixed experience.
I used Skyscanner & Kayak to research flights and they cost just over £1300 for the 3 of us on Air Kuwait (which is fine) changing planes in Kuwait. Get good travel insurance whoever you fly and look carefully at their definitions of Scheduled Airline Failure.
We all really really loved Sri Lanka - it’s a beautiful country with genuinely nice people you can only wish well. 3 days after we got back the bombings happened. I understand security (which was really relaxed when we were there had tightened up a lot since.
If you’ve any questions at all, happy to answer them!