Hi Michael, Nitra is not the most exciting town in Slovakia but your choices are good ones. Banska Bystrica is a lovely town, as is Banska Stiavnica though BS is much smaller (you can 'do it' in a day). Brno is okay but nothing very special. I've not yet been to Trnava. If you are into mountains, I would recommend going further East to either the Tatras, or, even more spectacular, the Slovak Paradise area, not far from Spissky Nova Ves, which has a direct train connection with Bratislava. A one day hike in the Slovak Paradise area would be my choice. Hope you have a great trip.
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Jeremy

Thanks for the response.

Having checked bus and trains I think the Tatras are further than I want to go. It does look spectacular though.

Well, Nitra is where the summer course is so that's not a choice. I think it looks interesting enough though.

I'm leaning mostly towards Banská Štiavnica at the moment. It's about 3 hours by bus from Nitra, and going back to Bratislava I can take the train (which I gather is pretty scenic down the valley) in plenty of time to make my planned early evening flight from Vienna. Any recommendations on places to stay? I tend to prefer pensions to big hotels.

I don't think you'll have a problem finding a pension in BS though I only spent a day there so can't recommend anything personally. I would recommend the divná pani caffé http://www.obedovat.sk/banskobystricky-kraj/Restauracia_3181_Divn%C3%A1_pani_caff%C3%A9 for something a little unusual.