A good choice would be some of our Nautical lighting made of brass, copper and stainless steel. These hold up best to harsh elements found living in a home by the salt water. Cast brass outdoor fixtures withstand corrosive salt environments and the piece will patina nicely with age.  

It is best to determine first what the style of your space is as well as the dining room table shape/direction. Decide on the overall feel of the home for the style choice: formal homes go with glass beads, brass or crystal. For a coastal, casual home try a driftwood, seashell or wood piece. For modern coastal, go with a clean-lined linear pendant style or polished nickel in finish.

You want the chandelier to be a focal point but not overwhelm the space.  If a dining room is 15' x 20', then the diameter of your chandelier should be in the neighborhood of about 35 inches. For the clearance in the dining room, another guide is that the chandelier should be 1/2 to 3/4 inches the width of the dining table as to not over-power the space. A linear chandelier looks best with a rectangular table and an oval or circular chandelier looks good with a round table. In order to determine the height of the chandelier, it is important to take into account the over all scale of the room and hang it allowing a clearance of 30 -32 inches above the dining table. 

The best nautical lighting would be made of brass, ability to take UL wiring and be surface mountable so that it can be adhered to the top of the piling post.

Pendants can be hung separately or hung from one rod/chain and have a linear fixture drop from that. The amount of lights depends on the size of the island.  Space the pendant light every 2'-2'-6 inches above a kitchen island and keep in mind the size of the light as to not overpower the island size: length & depth. Smaller Islands 4'-5' in length pair well with a single large pendant or two smaller pendants. Large kitchen islands of 6' plus, require two to three pendants spread out so the light covers the work surface well. 

Also consider do you want this as task lighting or ambient lighting? It's always nice to add a dimmer option when using the island lighting as ambient lighting. 

Lighting does not need to match throughout the home although it's best to maintain a few finish choices and not mix too many. For instance, if the table lamps are nickel and glass, maybe keep nickel as the finish on the pendant and chandelier. Keep a theme or style consistent if you do mix metals and materials often.

Sconce lighting best suits passageways, flanking a piece of art or a mirror on a focal point wall/in the bathroom. Sconces look great on the exterior of the home to illuminate the entrance.

If you have interior wall sconces, a good placement is to mount them to accent art or mirrors is 6' above the finished floor when when the ceiling is 8'. For 9' plus, mount them an extra 6 inches.