I realize that I can ping the different regions at http://speedtest-tor1.digitalocean.com/ but are there published ping times between the different regions (without me spinning up droplets and pinging them myself)?
I did some testing with my own Droplets and got the following data. Results could vary based on routing, Internet conditions, hypervisor load, etc., but hopefully this is a good starting point. You can use the usual grep, sort, and so on to narrow down the list.
from to min avg max mdev
f:ams2 t:ams2 0.040 0.059 0.275 0.032
f:ams2 t:ams3 0.898 1.124 1.437 0.129
f:ams2 t:blr1 138.613 138.715 139.054 0.224
f:ams2 t:fra1 6.845 6.978 7.411 0.118
f:ams2 t:lon1 11.303 11.434 11.682 0.161
f:ams2 t:nyc1 93.167 93.299 93.732 0.322
f:ams2 t:nyc2 99.329 99.547 100.528 0.437
f:ams2 t:nyc3 78.971 79.399 80.485 0.470
f:ams2 t:sfo1 164.883 165.011 165.217 0.280
f:ams2 t:sfo2 149.449 149.659 153.752 0.700
f:ams2 t:sgp1 339.653 339.886 340.139 0.419
f:ams2 t:tor1 95.862 98.325 106.832 2.689
f:ams3 t:ams2 0.860 1.103 1.404 0.128
f:ams3 t:ams3 0.021 0.038 0.059 0.011
f:ams3 t:blr1 140.728 140.798 141.078 0.267
f:ams3 t:fra1 6.782 6.850 6.938 0.089
f:ams3 t:lon1 6.434 6.495 6.631 0.112
f:ams3 t:nyc1 100.365 100.449 100.885 0.365
f:ams3 t:nyc2 90.764 90.968 93.138 0.511
f:ams3 t:nyc3 91.280 91.378 91.769 0.335
f:ams3 t:sfo1 159.194 159.288 159.448 0.125
f:ams3 t:sfo2 151.976 154.697 183.006 5.640
f:ams3 t:sgp1 320.547 320.640 320.825 0.362
f:ams3 t:tor1 101.619 104.223 112.711 2.761
f:blr1 t:ams2 138.648 138.874 142.248 0.647
f:blr1 t:ams3 140.771 140.862 141.073 0.503
f:blr1 t:blr1 0.019 0.032 0.054 0.009
f:blr1 t:fra1 143.041 143.103 143.206 0.435
f:blr1 t:lon1 154.127 154.172 154.254 0.249
f:blr1 t:nyc1 212.354 212.420 212.621 0.481
f:blr1 t:nyc2 203.972 204.119 204.629 0.407
f:blr1 t:nyc3 210.540 210.605 210.954 0.530
f:blr1 t:sfo1 250.825 250.894 251.058 0.643
f:blr1 t:sfo2 252.730 252.811 252.939 0.673
f:blr1 t:sgp1 91.072 91.238 91.883 0.407
f:blr1 t:tor1 234.763 234.943 237.501 0.796
f:fra1 t:ams2 6.861 6.961 7.136 0.092
f:fra1 t:ams3 6.763 6.878 7.942 0.175
f:fra1 t:blr1 141.391 141.458 141.563 0.420
f:fra1 t:fra1 0.014 0.023 0.046 0.008
f:fra1 t:lon1 18.733 18.848 19.152 0.149
f:fra1 t:nyc1 81.428 81.582 86.900 0.853
f:fra1 t:nyc2 84.878 85.039 85.291 0.315
f:fra1 t:nyc3 83.103 83.180 83.275 0.379
f:fra1 t:sfo1 168.601 168.663 168.765 0.500
f:fra1 t:sfo2 168.933 169.033 169.144 0.321
f:fra1 t:sgp1 197.451 197.658 198.132 0.166
f:fra1 t:tor1 113.986 115.724 121.993 1.783
f:lon1 t:ams2 11.269 11.422 12.081 0.166
f:lon1 t:ams3 6.368 6.467 6.625 0.098
f:lon1 t:blr1 154.134 154.228 154.667 0.496
f:lon1 t:fra1 18.754 18.864 19.040 0.068
f:lon1 t:lon1 0.021 0.029 0.040 0.007
f:lon1 t:nyc1 73.517 73.590 74.071 0.352
f:lon1 t:nyc2 68.118 68.344 69.496 0.339
f:lon1 t:nyc3 74.069 74.162 74.271 0.236
f:lon1 t:sfo1 145.143 145.270 145.420 0.121
f:lon1 t:sfo2 144.158 144.304 144.928 0.418
f:lon1 t:sgp1 191.727 191.935 192.301 0.483
f:lon1 t:tor1 84.874 86.818 91.808 1.675
f:nyc1 t:ams2 93.119 93.249 93.617 0.272
f:nyc1 t:ams3 100.320 100.411 100.563 0.373
f:nyc1 t:blr1 212.300 212.367 212.605 0.323
f:nyc1 t:fra1 81.382 81.460 81.893 0.377
f:nyc1 t:lon1 73.500 73.569 73.725 0.328
f:nyc1 t:nyc1 0.024 0.031 0.039 0.008
f:nyc1 t:nyc2 0.864 1.170 10.134 1.282
f:nyc1 t:nyc3 1.442 1.559 1.977 0.096
f:nyc1 t:sfo1 77.116 77.186 77.391 0.313
f:nyc1 t:sfo2 76.255 76.331 76.640 0.207
f:nyc1 t:sgp1 252.959 253.127 253.423 0.624
f:nyc1 t:tor1 15.793 17.062 21.958 1.533
f:nyc2 t:ams2 99.349 99.618 100.861 0.406
f:nyc2 t:ams3 90.697 90.922 92.663 0.486
f:nyc2 t:blr1 205.766 205.940 207.435 0.334
f:nyc2 t:fra1 84.939 85.055 86.354 0.456
f:nyc2 t:lon1 68.154 68.250 68.603 0.164
f:nyc2 t:nyc1 0.873 1.031 2.429 0.233
f:nyc2 t:nyc2 0.035 0.057 0.167 0.019
f:nyc2 t:nyc3 1.252 1.424 1.909 0.136
f:nyc2 t:sfo1 81.272 81.415 81.760 0.365
f:nyc2 t:sfo2 78.321 78.560 81.371 0.571
f:nyc2 t:sgp1 254.019 254.156 254.399 0.283
f:nyc2 t:tor1 15.791 17.240 23.452 1.657
f:nyc3 t:ams2 78.980 79.269 80.357 0.353
f:nyc3 t:ams3 91.239 91.352 91.606 0.367
f:nyc3 t:blr1 212.248 212.320 212.539 0.311
f:nyc3 t:fra1 83.159 83.209 83.308 0.333
f:nyc3 t:lon1 74.050 74.157 74.224 0.126
f:nyc3 t:nyc1 1.488 1.556 1.724 0.042
f:nyc3 t:nyc2 1.261 1.408 1.793 0.087
f:nyc3 t:nyc3 0.019 0.033 0.065 0.008
f:nyc3 t:sfo1 79.816 79.935 80.277 0.260
f:nyc3 t:sfo2 78.820 78.946 79.381 0.335
f:nyc3 t:sgp1 250.023 250.193 251.362 0.728
f:nyc3 t:tor1 16.397 17.972 24.016 1.791
f:sfo1 t:ams2 164.892 164.995 165.116 0.448
f:sfo1 t:ams3 159.248 159.322 159.493 0.312
f:sfo1 t:blr1 251.954 252.079 252.195 0.675
f:sfo1 t:fra1 168.599 168.685 168.845 0.223
f:sfo1 t:lon1 145.206 145.298 146.816 0.526
f:sfo1 t:nyc1 77.129 77.183 77.312 0.162
f:sfo1 t:nyc2 81.313 81.543 82.325 0.402
f:sfo1 t:nyc3 79.811 79.964 81.188 0.335
f:sfo1 t:sfo1 0.019 0.042 0.079 0.010
f:sfo1 t:sfo2 1.265 1.354 1.464 0.068
f:sfo1 t:sgp1 174.157 174.284 174.428 0.380
f:sfo1 t:tor1 63.214 63.444 65.445 0.381
f:sfo2 t:ams2 149.420 149.548 149.731 0.535
f:sfo2 t:ams3 151.967 153.757 164.331 2.461
f:sfo2 t:blr1 252.702 252.860 255.059 0.740
f:sfo2 t:fra1 168.964 169.095 171.180 0.325
f:sfo2 t:lon1 144.206 144.270 144.354 0.417
f:sfo2 t:nyc1 76.254 76.326 76.534 0.329
f:sfo2 t:nyc2 78.306 78.474 79.292 0.297
f:sfo2 t:nyc3 78.862 78.955 79.141 0.376
f:sfo2 t:sfo1 1.309 1.385 1.532 0.069
f:sfo2 t:sfo2 0.024 0.031 0.043 0.005
f:sfo2 t:sgp1 169.442 169.581 169.943 0.583
f:sfo2 t:tor1 63.040 63.270 66.089 0.594
f:sgp1 t:ams2 339.717 339.905 340.043 0.429
f:sgp1 t:ams3 320.517 320.758 325.287 0.792
f:sgp1 t:blr1 91.051 91.195 91.485 0.370
f:sgp1 t:fra1 197.507 197.666 197.884 0.365
f:sgp1 t:lon1 191.816 191.983 192.141 0.246
f:sgp1 t:nyc1 252.982 253.131 253.290 0.590
f:sgp1 t:nyc2 254.122 254.275 255.251 0.477
f:sgp1 t:nyc3 250.067 250.204 250.435 0.674
f:sgp1 t:sfo1 174.089 174.256 174.436 0.432
f:sgp1 t:sfo2 169.397 169.576 169.754 0.384
f:sgp1 t:sgp1 0.021 0.049 0.086 0.017
f:sgp1 t:tor1 237.888 238.073 238.873 0.619
f:tor1 t:ams2 95.777 96.738 99.263 0.788
f:tor1 t:ams3 101.702 102.986 111.426 1.618
f:tor1 t:blr1 234.777 234.906 235.701 0.564
f:tor1 t:fra1 113.947 115.101 120.405 1.366
f:tor1 t:lon1 84.981 87.273 96.185 2.869
f:tor1 t:nyc1 15.982 19.497 29.091 2.983
f:tor1 t:nyc2 15.844 18.020 27.312 2.568
f:tor1 t:nyc3 16.439 21.813 34.928 4.558
f:tor1 t:sfo1 63.247 63.449 64.861 0.298
f:tor1 t:sfo2 62.985 63.107 63.917 0.192
f:tor1 t:sgp1 237.886 238.145 240.014 0.702
f:tor1 t:tor1 0.028 0.051 0.239 0.028