Re: Remote apps
With you there - when the phone's ringing or your partner is yelling at you to turn it down, a standard, 'always-on' infrared remote is the way to go.
I've also yet to find an 'app' with the required features that is even close to usable without having to look at the blasted thing. The raised, tactile nature of a conventional remote means that, after a short while, most people can operate the thing without really looking, save for when you first pick it up and position your hand. Even then, most well-designed remotes are contoured so your hand generally slips into the same position each time.
And, while remotes can (and do) end up down the back of the couch, I don't think I've had to search the house for one, finding it in the bathroom or under the bedspread or in my partner's bag. That's because it's not overly useful in any of those places. A tablet/smart-phone, however, is far more likely to go walking. So, either buy a dedicated device for the system or be prepared to argue about whether changing tracks is more important than an Angry Birds high score. Even then, if you have it controlling multiple devices in multiple rooms, you may have to choose between the ability to pause your movie in the lounge or you partner's ability to change the radio station in the bedroom. A device in each room is a very nice solution but far from cheap!
Sure you might say that most people have a smart phone these days but, even imagining that that is the case, you end up with an angry wife, unable to call you because you left your phone in the study again after using it to cue up the ultimate Smiths playlist.
Of course, a 'smart' device can do much more and generally with a much richer (or even customisable) interface and a WLAN-capable device has the advantage of being useful from locations without line-of-sight; something quite handy with multi-room systems like the Sonos.