Hello Parky, I’ve lived in Brighton all my life and can safely say whoever told you Brighton is dangerous is talking rubbish. There are a couple of places on the very outskirts of Brighton that are ‘rough’ council estates but you wouldn’t be anywhere near them if you stay in central Brighton, they would only be considered not to walk through after dark which you wouldn’t!
All City’s are dangerous if you know where to go after dark, but during the day you will be fine. Just as you would anywhere else keep your wits about you, preferably use an over body handbag and stay central. The Gatwick to Brighton express train takes about 50 minutes with only a few stops (used to be 8 minutes past the hour) as you come out of the station there will be loads of taxis, might I suggest getting in a saloon taxi if you’re mobility is impaired like mine, do find London cabs difficult! The Hotel DuVin is pleasant as is the Old Ship (think it’s called that, google will tell you, as is the Grand. Hotel DuVin is almost on the seafront and central to the Lanes, the old ship is more or less overlooking the Brighton Pier. The Lanes are lovely and both the hotels back on to them and the North Lanes are eclectic, full of students and interesting if that’s what floats your boat (personally I prefer The Lanes). Maybe get a bus along to Rottingdean Village for a little stroll and cuppa or an ice cream or get the bus to Eastbourne for the day if you fancy a little ride out one day and some shopping.
My advice would be not to go to Brighton first week of August as its Pride week and absolutely heaving of people. Another nice place is a bus to Hove, (Portland Road) there’s plenty of shops and restaurants and in Hove seafront there’s the BA flight, Brighton & Hove’s answer to the London Eye. On the seafront towards Hove on the corner of Russell place (next to Preston street) is the best fish & chip restaurant in Brighton.
One last place the Royal Pavilion is worth a visit as it’s recently had a bit of a makeover.
I do hope you manage to persuade your sister to go to Brighton because if you haven’t been you will find it interesting.
Enjoy your break.