I went to Paris to celebrate my 16th birthday. Although it was the beginning of September, it was very warm and sunny, just the perfect weather for some sight-seeing!
The tourist attraction you've got to visit when in Paris is obviously the Eiffel Tower. The view on Paris from the second floor is simply amazing! The white architecture looks magical, a real breath-taking view! Although the queue for the tickets is always very long, it is definitely worth the wait. And if you get hungry, I recommend buying fries from a chippy stand next door. Ticket prices for the Eiffel Tower entrance vary between €7,00 and €11,00.
The Eiffel Tower looks just as nice at night, when it is all lit up with lights, so make sure to check it out, whilst out on an evening walk ;)
In a convenient place, right opposite the Eiffel Tower you'll be able to find the Gardens of the Trocadero, which look absolutely stunning!
Another place you've got to see is the Arc de Triomphe de l'Etoile. The Triumphal Arch honours those who fought and died in the French Revolutionary. It's a really nice piece of architecture and a perfect spot for some photos.
Whether you're making it a family trip or you're a bit of a kid yourself, you should go to the Disneyland Paris Resort and enjoy some rides. I would especially recommend the spaceship ride, which is a roller-coaster with a 360 degrees turn! Be patient though, when visiting Disneyland at peak time, be prepared to wait around 60-80 minutes in a queue for a ride that lasts about 3 mins! The resort is divided into two parks, and there is no way you will be able to go through all the attractions within one day.
When the sun goes down, Paris is still alive so don't be afraid to walk down the main streets and visit all the charming restaurants and cafe's. It is especially nice in summer, when you can drink a cocktail outside whilst enjoying the view on the Eiffel Tower.
If you're short on money and you find Paris accommodations too expensive, try finding a hotel in towns surrounding central Paris. An example of such town is Val d'Europe, which has an easy access to central Paris, as well as is ridiculously close to the Disneyland Resort, so it might be worth looking into.
Overall, Paris is a place you have to visit at least once in your lifetime! It is very romantic, the architecture is amazing and although it is a bit pricey, you won't regret it ;)