Stayed at the Martini in 2003 also during opera season. Bedroom still immaculately clean, bed comfortable, chambermaids helpful and welcoming, bed linen and towels changed daily. The big plus is how quiet it is at night. Yes, it's slightly away from the centre, but I've stayed in several central hotels where there is traffic noise all night. The breakfast buffet is good (especially for Italy), and 24 hr self-service tea/coffee is a good idea. Also, apparently the 2 (small) bottles of water in the minibar are free each day. We didn't know until we checked out and tried to pay.
Bus no.62 stops 5 mins from hotel, near the Porta Palio, and is useful for getting to Piazza della Erbe, Piazza dei Signori and Juliet's balcony. Definitely recommend buying the Verona Card: free access to the most important sites plus free travel on buses, you very quickly cover the cost EUR10 for 1 day, EUR15 for 3 days. Hotel sells 1 day, you have to go into town or the station to buy a 3-day card.
Two churches highly recommended and within walking distance: St. Bernardino (with the very elegant Pellegrini chapel). and St. Zeno Maggiore (dedicated to St Zenon, a black African who was the 8th Bishop of Verona and died in 380. Look out for his statue: it's said he was always smiling.) From St Zeno, it's a nice walk back by the river, on the Rigaste San Zeno, to Castelvecchio and the typically crenallated bridge of the De la Scala (Scaliger) family.