Planning to come to Thailand very soon, decided to apply for electronic visitor visa, but it asked for flight number and accommodations which I don’t have either yet(was planning to travel to different destinations, and just book mostly last minute through booking .Com)now I’m thinking I just will get visa exempt for 30 days, and extend another 30, I was going to book a flight and stay 56 days? 
Any advantage to continue  and get visitor visa?