There are direct flights from Kathmandu to Bangkok with Thai Airways and the flag carrier Nepal Airlines. Currently Nepal Airlines doesn't offer yet an online booking system. You can make reservations through agencies. One-way tickets from Kathmandu to Bangkok cost USD 220 (including all taxes), Singapore, Hong Kong with Dragon Air/Cathay Pacific. ArkeFly flies direct to Europe (Amsterdam, Netherlands). Many European destinations can be reached via Doha with Qatar Airways, Abu Dhabi with Etihad, Dubai with Emirates or the low cost carrier FlyDubai, Bahrain with Gulf Air. Flights are also available via Delhi on Jet Airways and UAE on Air Arabia.
Nepal's Tribhuvan International Airport is located just outside of the Ring Road in Kathmandu. The terminal is a one-room brick building with a large wooden table serving as both customs and immigration. Tourist visa of 15 days or more is available on arrival. Money can be changed to the local currency as well, but these services are only available directly after scheduled arrivals.
Outside the airport, all 'representatives' of the tourist industry are required to remain 10 meters (about 30 feet) from the front door. This does not prevent them from waving large signs and yelling in an attempt to encourage you to choose them as your guide/taxi/hotel/luggage carrier. Make your choice before crossing the line, or better yet, arrange your first night's accommodation before you arrive and ask the hotel to send someone to meet you. Many hotel and guest houses offer complimentary pick up and delivery from the airport. Fixed priceTaxis are also available before you exit the building but you may get a cheaper fare if you are willing to haggle. As always, negotiate the price beforehand with the driver. A taxi ride to Thamel or Boudha should be around 300 NRS. Otherwise, order a taxi at the pre-paid booth inside the airport, which costs 400+NRs (and rising). This is more than the normal taxi rate, but it saves the hassle of long negotiations.
By car or motorcycle:
It is quite easy to rent a car with a driver in Nepal, however you would need to haggle to get a reasonable price. If you come in summer, better take a car with AC. Car rental without a driver in Nepal is almost unheard of, as is renting a car in India and taking it across the border.
Many travellers drive from India on Royal Enfield motorcycles. Technically, foreigners have to pay customs at the borders but most don't bother. Selling the bike in Nepal is easy as other travelers are looking for bikes to ride back to India.
If you are coming from India you will find driving in Nepal a lot less chaotic! The roads are amazing and the new east-west highway currently under construction with support from the Japanese will open up new destinations for those interested in exploring Nepal by motor-bike.
Please check before hiring a motorbike on the current state of fuel. At time of writing (13DEC 09) there was large problems with fuel supply which can leave riders stranded. At time of writing, bike hire should be no more than 500Rs a day (Pulsar, Hero Honda, scooter) unless you are hiring an Indian Enfield.
Hirers are also notorious for trying to charge tourists large amounts of money on returning the bike for 'damage payment' that may not have been from you. Therefore make sure a thorough damage assessment with the hirer is carried out before departing and if the hirer tries to scam you on return go to local police.
The best route to explore nepal by road on motorcycle, is to enter from the border crossing of Banbasa- Mahendra Nagar, just after the border crossing, the Mahendra Highway (made with collaboration from India) is amazing to ride on.
Crossing the border requires you to pay a daily toll of 120 rs (Nepali) and a transport permit of 50 rs Nepali(one time), the cops can ask you for these two pieces of document anytime during the ride
There are Five border crossings open to tourists. The Sunauli-Bhairawa border crossing is the closest to Varanasi, the Raxaul-Birganj crossing to Patna, Kolkata, and Siliguri-Kakarbhitta is to Darjeeling. The Banbassa-Mahendrenagar border crossing in the extreme west of Nepal, is the closest to Delhi. The bahraich-Nepalganj border is the one closest to Lucknow which is the easiest destination by air or train from Delhi.
The crossing between Nepal and Tibet via Kerung is open to independent travelers entering Nepal, but only to organised groups entering Tibet.
Cargo and passanger trains operate between Sirsiya in southern Nepal, and the Indian town of Raxaul. However, except for Indians, foreigners are not allowed to cross border with it. Internal train network is limited to few kilometers of train network in Janakpur.
The point of entry and exit for tourist:
Tribhuvan International Airport, Kathmandu
Kakarvitta, Jhapa (Eastern Nepal)
ImmiBirganj, Parsa (Central Nepal)
Kodari, Sindhupalchowk (Northern Border)
Belahia, Bhairahawa (Rupandehi, Western Nepal)
Jamunaha, Nepalgunj (Banke, Mid Western Nepal)
Mohana, Dhangadhi (Kailali, Far Western Nepal)
Gaddachauki, Mahendranagar (Kanchanpur, Far Western Nepal)