Travel sites I have used and would recommend:

aa.com ~ airbnb.com ~ alltrails.com ~ booking.com ~ britishairways.com ~ citylink.co.uk ~ expedia.com ~ hostels.com ~ hostelworld.com ~ hostelz.com ~ hotels.com ~ irishrail.ie ~ kayak.com ~ kiwi.com ~ lyft.com ~ nationalexpress.com ~ orbitz.com ~ priceline.com ~ scotrail.co.uk ~ shiftcam.com ~ southwest.com ~ thetrainline.com ~ transportationforireland.ie ~ trivago.com ~ uber.com