Get the best speakers and deck you can afford. Bose makes some really great marine speakers. I have a CD player in my boat, and don't have many issues with it skipping. I have another buddy that just put XM Radio in his boat.
Mount the speakers flush in your console, and think about getting 2 sets. 1 set may not be enough to have sound when running.
I bought my radio from Best Buy with 4 year warranty,I think the extended warranty was $20 have had the unit replaced 3 times for free,the radios only last a year or two before corrosion gets the best of them.
speakers are looked at as disposable they work for 1-2 years and they are trash...either blown out or stop working. I found some Aquaonics that had a life time warranty but dont sound that great... on the fourth set need i say more but free is free. I also put a set on the T-Top to face the driver (me) that are a little better and sound good at wot.
radio is a Jensen that has 7yrs on it...... so now it is sure to break on the next trip
I would look hard a SX radio on my next go around that would be nice to have radio 120mi out .. ..I get tired of the same music over and over and over