Hi, I live in the USA, in Ohio, and have some suggestions for your USA trip.
Maybe stay in NYC 4 or 5 days at the most, 2 or 3 days Boston, 1 or 2 days Niagara Falls. Stay in a small hotel on the Canadian side of the Falls if possible, or spend most of your time on this side of the falls as this side is much more interesting and more beautiful than the USA side. You can find small, friendly hotels within one mile walk uphill from the falls. Or to save money, stay at the youth hostel on the USA side of the falls. I stayed there about 3 years ago. It was very nice, but a very long walk (a few miles to the falls), so best to take a local bus (inconvenient at times, or rent a bicycle, or share car ride with other guests if possible). The hostel owner is a woman who is friendly and helpful. Be sure to see the falls at night, after dark. Take the boat ride "Maid of the Mist" and take the walk down behind the Falls (Canadian side, I think?). THe company that charges admission for both of these gives you a free raincoat to keep you dry (sort of, but you should still plan to get a little bit wet from the water). Free movie about the history of the falls, and maybe an IMAX movie that costs money.
I would suggest to add 3 full days in Washington DC. First, it's beautiful. And there are MANY free things to do that are very nice. All of the Smithsonian Museums are free (about 27 of them on different topics). The National Zoo is also free. They have a very efficient metro and bus system to get around. Buy a one day or 3-day metro ticket. Find an expensive hostel or college room within a few blocks of the metro. The national monuments are beautiful and inspiring, especially the Lincoln Monument in the evening and after dark. Many parks and beautiful places to walk, ride a bike, relax, people watch, etc. Lots of culture....ethnic restaurants, art galleries, and small shops. Free planetarium show at National Geographic.
If you will be here 4 July, this is the USA's Birthday, or "Independence Day" with parades and marching bands during daylight and fireworks after dark in every city and town in the nation. So be sure to participate somewhere. They are usually free, but some places charge for premium seating in a stadium, etc.
Many cities and towns have outdoor music concerts in parks in evenings in the summer. Most are free, or some cost money (ie symphony). Most are Thursday through Sunday evenings.
Drive quickly on the interstate freeway system from Niagara Falls to the western USA. It might take about 3 days, or 30+ hours driving. Maybe stop in one or two small towns along the way for a quick look, but skip most of the country from Niagara Falls to the Rocky Mountains. The Rocky Mountains and west coast will be much more interesting and more beautiful than the midwest. (I live in the midwest and have traveled all over the country, so I know). If you don't have pre-paid hotels, Super 8, Motel 6 and Red Roof Inn are 3 examples of nationwide hotel chains that are inexpensive by USA prices, and have many locations along the interstate freeways.
Try to visit the Grand Canyon (South Rim)(at least one day) and Yellowstone Park (3 full days minimum). You definitely need to rent a car for Yellowstone. Amazing wildlife viewing in early morning and evening: elk, buffalo, etc. Both are COLD at night. Pay attention to ELEVATION. Places in the south at high elevation (over 5000 ft) are very cold at night. At Yellowstone, it can get 32 degrees F (freezing) or colder every night all year. Yellowstone has wonderful thermal features light hot springs, boiling mud pots, geysers, etc, similar to on the North Island of New Zealand. There is a very nice Lodge or Inn there, but it is very expensive. Speed limit is 35 mph to 45 mph everywhere (slow), and Yellowstone Park is larger than the state of Rhode Island. It is HUGE and takes many hours of driving from one end to the other. There are some campgrounds there, but I don't know if you can rent a cabin or tent, as I brought my own tent. Some campgrounds have hot showers, but some may be cold showers only. Check ahead.
Spend at least 2 weeks on the west coast, preferably California. LOTS to see and do, and quite beautiful, although it can be expensive. You can find free and low cost things to do everywhere, and the ocean beaches are free in most places.
Larger grocery stores in the USA have salad bars, pre-made sandwiches for sale, and hot food counters where you can get meals to go and eat them in a park nearby. This can be cheaper than restaurants, although not always, but the food is fresh. In some states there is no sales tax on food purchased in grocery stores, and no waitress to tip, so both of these things save a little money.
Have a great year!
