You have to define the data rate you are assuming with your design. You say 4 sensors, floating point, 1000Hz sampling rate and 10seconds. That may leed to 16kB/sec or 50kB/sec based on the format stored.
I personally would go with MRAM (512kBytes per chip, 8pin, SPI) nonvolatile and w/ the above fat16lib's filesystem when talking 10sec recording at the guessed data rates above. For more demanding application you may consider the 8MB ramdisk.