What to upgrade first?

Two good routes are available to you. You could take that $1000 you have in your budget and buy speakers. Put off amplification for another year. Then, again spend $1000 on that area. This strategy will buy you a system several levels higher than spending $500 on either speakers or amplification. And, I would keep a keen eye towards used equipment. For $1000, you can buy the kind of speakers you can live with indefinitely. Lots to choose there. Only limited by your likes and dislikes. Alternatively, you could buy the amplification now(Anthem, Audio Refinement, Creek, Jolida, LFD, Musical Fidelity, etc.), and spend $120 - $150 redoing your current speakers. Vifa drivers, Solen caps, Ohmite resistors, and 14 gauge air core inductors(if you have coils...). While you are in there, lay down a bead of RTV silicone along all cabinet joinery. Also use a gasket between your drivers and cabinet. You WILL be surprised. And you'll get another two years out of the speakers. Either way, for wire, use AudioQuest Turquoise interconnect and Type 6 speaker cable. You'll get more mileage out of these two cheap cables than most people will admit. They are very neutral in sound, and will lend themselves to most directions you will be headed down the road. When the rest of your system is finalized, then you can move up to better cable.