I have personally planned and booked many trips across the world by using these websites and companies. I shall keep on evaluating and adding more in the list, check back again before you plan your next trip.
According to my experience, it's one of the best accommodation options; this site will connect you with homeowners who rent out their homes or apartments. It has over 3 million lodging listings in 65,000 cities and 191 countries. You can find your preferred accommodation in most parts of the city or country. It's really beneficial if you're travelling solo, this way you can interact more with localities.
This website lists over 1.4 million properties in 226 countries, it is quite helpful in finding cheap accommodations including hotels and hostels. Their no money down policy is useful especially when you need hotel booking for visa purposes.
If you are on a tight budget and don't mind your privacy much, you can find people’s couches or spare rooms for free on this website. Not only this, but it’s also a great way to meet locals moreover it has many groups where you can meet up for events in your destination city.
If you are quite keen on mingling with locals and learning about new cultures and food, then this is the site for you. It lets you find interest group in many cities across the world. Some groups on meetup also offer free city walking tours, arrange lunch/dinner meetups, blind wine tastings, adventure seeking events and photography in the city.
It compares prices from suppliers, including major airlines, through tiny travel agents. I have used it many times and prefer it over other search engine aggregators as it's simple and easy to use. Excellent tool to help travellers.
If you are heading to Europe and planning to hop from city to city or country to country, then I highly recommend getting a rail pass which comes in various options. I have used it myself, and it helped me save a lot of bucks. Though you can buy it from other companies as well, I recommend Eurail as they have offices in Dubai also.
It is a multimodal transport search engine that shows you how to get from point A to point B in the best and cheapest possible way. It is capable of long-distance (inter-city) trip planning as well as local (intra-city) journey planning. You can input any address, town or landmark as the origin and destination and it searches a database of flight, train, ferry, bus and driving routes to present route and price options for travelling to that destination.
It works with universities and other organisations to offer online courses and specialisations in a variety of subjects so if you are looking to learn photography or want to build on your creative writing skills you can choose from their over 2,000 courses. I have personally taken their 5-course specialisation "Photography Basics and Beyond: From Smartphone to DSLR" by Michigan State University, and it helped me improve my photography skills a lot.