Hungary advice needed

Hi guys!
Summer is coming and I become restless
:-)
Need pack and go, isn't it?
I'm thinking about Hungary, never have been there yet.
Shame to me!
All right, Budapest is a star, it's clear. But where else to go?

If this plan will come true - I am coming from Vienna (Austria) and flying home from Budapest. I can allow myself stay in Hungary about 7-10 days. In beginning of September.

Another potential trip is from Vienna and back during the last week of July. Lenth of the trip - up to 7 days.

In any case it will be budget travel, but if some family mmbrs join - then we even may to rent a car.
I will be glad to hear anything you wanna tell about travel in Hungary: where to go, what don't miss, what to let down, how are roads there and public transport? Where to sleep? How is the weather in July ? and in September?
Will appreciate advice about cheap and effective (relatively) transportation btween Venna and Hungary.
Any advice welcome!

Cheers,
Your Vanessa

Id say you should visit Szentendre .
Nice town close to Budapest, and Lake Balaton

Hungary and Budapest tourist guide:
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http://www.hungary-tourist-guide.com/
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http://cityguide.budapestrooms.com/transport.htm
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In Budapest, make sure you visit the museum, tour the parliament building by the Danube, and take the funicular across the river up to see the palace in the Old Town. Also maybe a cruise?

Not really that much outside Budapest. A lot of the locals go to Lake Balaton in summer but it's a lake. Not a lot there.

If you use any public transport, make sure you validate your ticket (put it into a "punch" machine.) I have seen people fined for not doing it.

Hello, Vanessa definitely come to Belgrade if you're visiting Hungary, in case you have time Belgrade is the capitol of Serbia... I recommend - Hostel Skadarlija Sunrise, you can find it at hostelbookers.com as well great hostel, great city... Serbia is the country with rich history... if you like to party, Belgrade is the place to be I live in Belgrade, in case you're coming, let me know, i can give you some more tips! Have a great day!
BTW, Hungary is awesome... I love Budapest... if you need a hostel, I recommend - "Paprika"... art exhibitions in Budapest are always wonderful... have fun!

thank you guys!
I will check up all your recommendations.
Keep talking, I'd like to receive more ideas.
What "don't miss" in Budapest? Accommodation is an issue itself.
thanks,
Vanessa